Setting -DCOMPILER_RT_TEST_TARGET_TRIPLE=armv6m-none-eabi will enable the build of builtin functions ARMv6m.
Currently, only those asms that support armv6m are added.
TODO:All asm sin ARM_EABI_Sources are ported for thumb1 so Thumb1_EABI_Sources will be deprecated.
Why not just add a test_target_arch inside the MATCHES "arm" below?