cmake HAVE_DARWIN_ATOMICS examples

google/mysql-protobuf storage/ndb/memcache/atomics.cmake :49 

CHECK_C_SOURCE_RUNS(
    "#include <libkern/OSAtomic.h>
     int main() {
       volatile int foo = 5; 
       OSAtomicAdd32(6, &foo);
       return (foo == 11) ? 0 : -1;
     }"
    HAVE_DARWIN_ATOMICS
  )

google/mysql-protobuf storage/ndb/memcache/atomics.cmake :76 

ELSEIF(HAVE_DARWIN_ATOMICS)