cmake HAVE_STRTOF examples

Froser/gamemachine src/3rdparty/openal-soft-1.19.1/CMakeLists.txt :567 

CHECK_FUNCTION_EXISTS(strtof HAVE_STRTOF)

ornladios/ADIOS2 thirdparty/ffs/ffs/CMakeLists.txt :307 

CHECK_FUNCTION_EXISTS(strtof HAVE_STRTOF)