cmake COMPILER_RT_HAS_FCF_PROTECTION_FLAG examples

Lewuathe/mlir-hello thirdparty/llvm-project/compiler-rt/cmake/config-ix.cmake :93

check_c_compiler_flag(-fcf-protection=full   COMPILER_RT_HAS_FCF_PROTECTION_FLAG)

CTSRD-CHERI/cheribsd contrib/subrepo-cheri-compiler-rt/cmake/config-ix.cmake :71

check_c_compiler_flag(-fcf-protection=full   COMPILER_RT_HAS_FCF_PROTECTION_FLAG)