cmake COMPILER_RT_HAS_LIBM examples

Lewuathe/mlir-hello thirdparty/llvm-project/compiler-rt/cmake/config-ix.cmake :192 

check_library_exists(m pow "" COMPILER_RT_HAS_LIBM)

trailofbits/polytracker polytracker/src/compiler-rt/cmake/config-ix.cmake :132 

check_library_exists(m pow "" COMPILER_RT_HAS_LIBM)

CTSRD-CHERI/cheribsd contrib/subrepo-cheri-compiler-rt/cmake/config-ix.cmake :169 

check_library_exists(m pow "" COMPILER_RT_HAS_LIBM)