cmake HAVE_C99_BOOL examples

Froser/gamemachine src/3rdparty/openal-soft-1.19.1/CMakeLists.txt :234

CHECK_C_SOURCE_COMPILES(
"int main(int argc, char *argv[])
 {
     volatile _Bool ret;
     ret = (argc > 1) ? 1 : 0;
     return ret ? -1 : 0;
 }"
HAVE_C99_BOOL)