Merge pull request #1333 from UncleGrumpy/stm32_build_config

Allow continuing to support 512k flash STM32 boards

For STM32 devices with 512k flash newlib-nano needs to be used otherwise the
compiled binary is too large to leave space for user applications.

These changes are made under both the "Apache 2.0" and the "GNU Lesser General
Public License 2.1 or later" license terms (dual license).

SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later

src/platforms/stm32/cmake/compile-flags.cmake

@@ -36,6 +36,7 @@ set(CXX_WARN_FLAGS "${COMMON_WARN_FLAGS}")
 # Use C and C++ compiler optimizatons for size and speed.
 if (${CMAKE_FLASH_SIZE} STREQUAL "ROM_512K")
 set(OPTIMIZE_FLAG "-Os")
+set(LINKER_FLAGS "${LINKER_FLAGS} -specs=nano.specs")
 else()
 set(OPTIMIZE_FLAG "-O2")
 endif()