cmake COMPILER_RT_HAS_LIBSTDCXX examples

Lewuathe/mlir-hello thirdparty/llvm-project/compiler-rt/cmake/config-ix.cmake :201 

check_library_exists(stdc++ __cxa_throw "" COMPILER_RT_HAS_LIBSTDCXX)

trailofbits/polytracker polytracker/src/compiler-rt/cmake/config-ix.cmake :156 

check_library_exists(stdc++ __cxa_throw "" COMPILER_RT_HAS_LIBSTDCXX)

CTSRD-CHERI/cheribsd contrib/subrepo-cheri-compiler-rt/cmake/config-ix.cmake :193 

check_library_exists(stdc++ __cxa_throw "" COMPILER_RT_HAS_LIBSTDCXX)