Add betterC to probePlatform calls

[LunaTheFoxgirl]

When building D projects without a runtime for new platforms, dub will fail when there's no druntime for said platform.

This PR makes all the probePlatform calls use betterC so that runtime-less platforms can be built for with dub.

I need this for building D projects for the SuperH CPU architecture (as used in the SEGA Dreamcast and SEGA Saturn)

NOTE: This PR could be improved by checking the compiler versions before calling probePlatform, to ensure that older compilers without betterC support for the platform probe still works.

[github-actions]

✅ PR OK, no changes in deprecations or warnings

Total deprecations: 14

Total warnings: 0

Build statistics:

 statistics (-before, +after)
-executable size=5357768 bin/dub
+executable size=5361864 bin/dub
 rough build time=80s

Full build output

DUB version 1.33.1, built on Aug 26 2023
LDC - the LLVM D compiler (1.34.0):
  based on DMD v2.104.2 and LLVM 16.0.6
  built with LDC - the LLVM D compiler (1.34.0)
  Default target: x86_64-unknown-linux-gnu
  Host CPU: icelake-server
  http://dlang.org - http://wiki.dlang.org/LDC


  Registered Targets:
    aarch64     - AArch64 (little endian)
    aarch64_32  - AArch64 (little endian ILP32)
    aarch64_be  - AArch64 (big endian)
    amdgcn      - AMD GCN GPUs
    arm         - ARM
    arm64       - ARM64 (little endian)
    arm64_32    - ARM64 (little endian ILP32)
    armeb       - ARM (big endian)
    avr         - Atmel AVR Microcontroller
    bpf         - BPF (host endian)
    bpfeb       - BPF (big endian)
    bpfel       - BPF (little endian)
    hexagon     - Hexagon
    lanai       - Lanai
    loongarch32 - 32-bit LoongArch
    loongarch64 - 64-bit LoongArch
    mips        - MIPS (32-bit big endian)
    mips64      - MIPS (64-bit big endian)
    mips64el    - MIPS (64-bit little endian)
    mipsel      - MIPS (32-bit little endian)
    msp430      - MSP430 [experimental]
    nvptx       - NVIDIA PTX 32-bit
    nvptx64     - NVIDIA PTX 64-bit
    ppc32       - PowerPC 32
    ppc32le     - PowerPC 32 LE
    ppc64       - PowerPC 64
    ppc64le     - PowerPC 64 LE
    r600        - AMD GPUs HD2XXX-HD6XXX
    riscv32     - 32-bit RISC-V
    riscv64     - 64-bit RISC-V
    sparc       - Sparc
    sparcel     - Sparc LE
    sparcv9     - Sparc V9
    spirv32     - SPIR-V 32-bit
    spirv64     - SPIR-V 64-bit
    systemz     - SystemZ
    thumb       - Thumb
    thumbeb     - Thumb (big endian)
    ve          - VE
    wasm32      - WebAssembly 32-bit
    wasm64      - WebAssembly 64-bit
    x86         - 32-bit X86: Pentium-Pro and above
    x86-64      - 64-bit X86: EM64T and AMD64
    xcore       - XCore
   Upgrading project in /home/runner/work/dub/dub/
    Starting Performing "release" build using /opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/ldc2 for x86_64.
    Building dub 1.34.0+commit.31.gb14f9177: building configuration [application]
source/dub/dependency.d(917,18): Deprecation: scope variable `this` assigned to non-scope parameter `oth` calling `opEquals`
source/dub/dependency.d(920,30): Deprecation: scope variable `this` assigned to non-scope parameter `a` calling `doCmp`
source/dub/dependency.d(921,27): Deprecation: scope variable `this` assigned to non-scope parameter `b` calling `doCmp`
source/dub/dependency.d(939,26): Deprecation: scope variable `this` assigned to non-scope parameter `oth` calling `opEquals`
source/dub/internal/configy/Exceptions.d(130,34): Deprecation: reference to local variable `buffer` assigned to non-scope anonymous parameter
source/dub/internal/configy/Exceptions.d(134,34): Deprecation: reference to local variable `buffer` assigned to non-scope anonymous parameter
source/dub/internal/configy/Exceptions.d(248,27): Deprecation: `@safe` function `formatMessage` calling `formattedWrite`
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/write.d(537,34):        which calls `std.format.spec.FormatSpec!char.FormatSpec.writeUpToNextSpec!(void delegate(in char[]) @safe).writeUpToNextSpec`
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/spec.d(258,33):        which wouldn't be `@safe` because of:
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/spec.d(258,33):        scope variable `this` assigned to non-scope parameter `e` calling `put`
source/dub/internal/configy/Exceptions.d(250,27): Deprecation: `@safe` function `formatMessage` calling `formattedWrite`
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/write.d(537,34):        which calls `std.format.spec.FormatSpec!char.FormatSpec.writeUpToNextSpec!(void delegate(in char[]) @safe).writeUpToNextSpec`
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/spec.d(258,33):        which wouldn't be `@safe` because of:
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/spec.d(258,33):        scope variable `this` assigned to non-scope parameter `e` calling `put`
source/dub/internal/configy/Exceptions.d(283,27): Deprecation: `@safe` function `formatMessage` calling `formattedWrite`
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/write.d(537,34):        which calls `std.format.spec.FormatSpec!char.FormatSpec.writeUpToNextSpec!(void delegate(in char[]) @safe).writeUpToNextSpec`
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/spec.d(258,33):        which wouldn't be `@safe` because of:
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/spec.d(258,33):        scope variable `this` assigned to non-scope parameter `e` calling `put`
source/dub/internal/configy/Exceptions.d(286,27): Deprecation: `@safe` function `formatMessage` calling `formattedWrite`
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/write.d(537,34):        which calls `std.format.spec.FormatSpec!char.FormatSpec.writeUpToNextSpec!(void delegate(in char[]) @safe).writeUpToNextSpec`
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/spec.d(258,33):        which wouldn't be `@safe` because of:
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/spec.d(258,33):        scope variable `this` assigned to non-scope parameter `e` calling `put`
source/dub/internal/configy/Exceptions.d(323,31): Deprecation: `@safe` function `formatMessage` calling `formattedWrite`
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/write.d(537,34):        which calls `std.format.spec.FormatSpec!char.FormatSpec.writeUpToNextSpec!(void delegate(in char[]) @safe).writeUpToNextSpec`
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/spec.d(258,33):        which wouldn't be `@safe` because of:
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/spec.d(258,33):        scope variable `this` assigned to non-scope parameter `e` calling `put`
source/dub/internal/configy/Exceptions.d(325,31): Deprecation: `@safe` function `formatMessage` calling `formattedWrite`
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/write.d(537,34):        which calls `std.format.spec.FormatSpec!char.FormatSpec.writeUpToNextSpec!(void delegate(in char[]) @safe).writeUpToNextSpec`
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/spec.d(258,33):        which wouldn't be `@safe` because of:
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/spec.d(258,33):        scope variable `this` assigned to non-scope parameter `e` calling `put`
source/dub/internal/configy/Exceptions.d(332,31): Deprecation: `@safe` function `formatMessage` calling `formattedWrite`
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/write.d(537,34):        which calls `std.format.spec.FormatSpec!char.FormatSpec.writeUpToNextSpec!(void delegate(in char[]) @safe).writeUpToNextSpec`
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/spec.d(258,33):        which wouldn't be `@safe` because of:
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/spec.d(258,33):        scope variable `this` assigned to non-scope parameter `e` calling `put`
source/dub/internal/configy/Exceptions.d(335,31): Deprecation: `@safe` function `formatMessage` calling `formattedWrite`
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/write.d(537,34):        which calls `std.format.spec.FormatSpec!char.FormatSpec.writeUpToNextSpec!(void delegate(in char[]) @safe).writeUpToNextSpec`
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/spec.d(258,33):        which wouldn't be `@safe` because of:
/opt/hostedtoolcache/dc/ldc2-1.34.0/x64/ldc2-1.34.0-linux-x86_64/bin/../import/std/format/spec.d(258,33):        scope variable `this` assigned to non-scope parameter `e` calling `put`
     Linking dub
STAT:statistics (-before, +after)
STAT:executable size=5361864 bin/dub
STAT:rough build time=80s

[LunaTheFoxgirl]

I've added a workaround for a GDC bug related to this, the platform check would fail because __ctfe is broken and will try to compile for runtime anyways.

The cursed multi-line pragma improves compatibility and has been tested across GDC, DMD and LDC. It also now fully does not depend on libphobos for output compilation which should speed it up too.

[Geod24]

Superseded by #2753
Sorry this wasn't merged earlier, and thank you for your work! Let us know if #2753 does not work for you for some reason.