cmake HAVE_C11_STATIC_ASSERT examples

Froser/gamemachine src/3rdparty/openal-soft-1.19.1/CMakeLists.txt :244

CHECK_C_SOURCE_COMPILES(
"int main()
 {
     _Static_assert(sizeof(int) == sizeof(int), \"What\");
     return 0;
 }"
HAVE_C11_STATIC_ASSERT)