Fix ucontext_t alignment in strict ansi mode

Using `cosmocc -std=c11` was causing `ucontext_t` to become misaligned.
This change also adds the GNU constants on x86_64 for accessing general
registers, so you will not need `#ifdef`s to support both Cosmo and GNU

libc/calls/ucontext.h

@@ -7,6 +7,32 @@ COSMOPOLITAN_C_START_
 
 #ifdef __x86_64__
 
+#if defined(_GNU_SOURCE) || defined(_COSMO_SOURCE)
+#define REG_R8      0
+#define REG_R9      1
+#define REG_R10     2
+#define REG_R11     3
+#define REG_R12     4
+#define REG_R13     5
+#define REG_R14     6
+#define REG_R15     7
+#define REG_RDI     8
+#define REG_RSI     9
+#define REG_RBP     10
+#define REG_RBX     11
+#define REG_RDX     12
+#define REG_RAX     13
+#define REG_RCX     14
+#define REG_RSP     15
+#define REG_RIP     16
+#define REG_EFL     17
+#define REG_CSGSFS  18
+#define REG_ERR     19
+#define REG_TRAPNO  20
+#define REG_OLDMASK 21
+#define REG_CR2     22
+#endif
+
 struct XmmRegister {
   uint64_t u64[2];
 };
@@ -31,7 +57,7 @@ struct thatispacked FpuState {
   uint32_t __padding[24];
 };
 
-typedef uint64_t greg_t;
+typedef long long greg_t;
 typedef greg_t gregset_t[23];
 typedef struct FpuState *fpregset_t;
 

libc/integral/c.inc

@@ -174,18 +174,9 @@ typedef struct {
 #endif
 
 #ifndef forcealign
-#ifndef __STRICT_ANSI__
 #define forcealign(bytes) __attribute__((__aligned__(bytes)))
-#else
-#define forcealign(bytes)
 #endif
-#endif
-
-#ifndef __STRICT_ANSI__
 #define thatispacked __attribute__((__packed__))
-#else
-#define thatispacked
-#endif
 
 #ifndef __STRICT_ANSI__
 #define printfesque(n)   __attribute__((__format__(__gnu_printf__, n, n + 1)))
@@ -727,8 +718,7 @@ void abort(void) wontreturn;
 #define __static_yoink_source(PATH)
 #endif
 
-#define __weak_reference(sym, alias)       \
-  __weak_reference_impl(sym, alias)
+#define __weak_reference(sym, alias) __weak_reference_impl(sym, alias)
 #define __weak_reference_impl(sym, alias)  \
   __asm__(".weak\t" #alias "\n\t"          \
           ".equ\t" #alias ", " #sym "\n\t" \