cmake COMPILER_RT_HAS_LIBATOMIC examples

Lewuathe/mlir-hello thirdparty/llvm-project/compiler-rt/cmake/config-ix.cmake :86 

check_library_exists(atomic __atomic_load_8 "" COMPILER_RT_HAS_LIBATOMIC)

CTSRD-CHERI/cheribsd contrib/subrepo-cheri-compiler-rt/lib/scudo/standalone/tests/CMakeLists.txt :46 

check_library_exists(atomic __atomic_load_8 "" COMPILER_RT_HAS_LIBATOMIC)