arch: ARM: set -mthumb, -mcpu, -mfpu and -mfloat-abi in linker flags

Some toolchains are built with multilib enabled in order to provide
multiple versions of the same library, optimized for different ABI
or architecture. They require the the ABI/architecture/CPU selection
options to be passed at linked time. This is important for example
when linking with newlib.

Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

CMakeLists.txt

@@ -162,6 +162,10 @@ zephyr_compile_options(
 )
 endif()
 
+zephyr_ld_options(
+  ${TOOLCHAIN_LD_FLAGS}
+)
+
 if(NOT CONFIG_NATIVE_APPLICATION)
 zephyr_ld_options(
   -nostdlib

cmake/compiler/gcc.cmake

@@ -82,15 +82,22 @@ else()
       -mthumb
       -mcpu=${GCC_M_CPU}
       )
+    list(APPEND TOOLCHAIN_LD_FLAGS
+      -mthumb
+      -mcpu=${GCC_M_CPU}
+      )
 
     include(${ZEPHYR_BASE}/cmake/fpu-for-gcc-m-cpu.cmake)
 
     if(CONFIG_FLOAT)
       list(APPEND TOOLCHAIN_C_FLAGS -mfpu=${FPU_FOR_${GCC_M_CPU}})
+      list(APPEND TOOLCHAIN_LD_FLAGS -mfpu=${FPU_FOR_${GCC_M_CPU}})
       if    (CONFIG_FP_SOFTABI)
         list(APPEND TOOLCHAIN_C_FLAGS -mfloat-abi=softfp)
+        list(APPEND TOOLCHAIN_LD_FLAGS -mfloat-abi=softfp)
       elseif(CONFIG_FP_HARDABI)
         list(APPEND TOOLCHAIN_C_FLAGS -mfloat-abi=hard)
+        list(APPEND TOOLCHAIN_LD_FLAGS -mfloat-abi=hard)
       endif()
     endif()
   elseif("${ARCH}" STREQUAL "arc")