cmake HAVE_MAC_BYTESWAP examples

taglib/taglib ConfigureChecks.cmake :71 

check_cxx_source_compiles("
        #include <libkern/OSByteOrder.h>
        int main() {
          OSSwapInt16(0);
          OSSwapInt32(0);
          OSSwapInt64(0);
          return 0;
        }
      " HAVE_MAC_BYTESWAP)