cmake HAVE_C_FLAG_ examples

google/filament third_party/civetweb/cmake/AddCCompilerFlag.cmake :23 

string(TOUPPER "HAVE_C_FLAG_${FLAG}" SANITIZED_FLAG)

bareos/bareos core/cmake/BareosCheckFunctions.cmake :89 

check_function_exists(chflags HAVE_CHFLAGS)

bareos/bareos core/cmake/BareosCheckSymbols.cmake :32 

message(STATUS "lchflags is a stub, setting HAVE_CHFLAGS to 0")