Cut glog include from folly/synchronization/RWSpinLock.h

Summary: [Folly] Cut `glog` include from `folly/synchronization/RWSpinLock.h`.

Reviewed By: meyering

Differential Revision: D6659300

fbshipit-source-id: 0f1b79d98be0656694f57667252a16acd54e2414

folly/synchronization/RWSpinLock.h

@@ -157,11 +157,8 @@ pthread_rwlock_t Read        728698     24us       101ns     7.28ms     194us
 
 #include <algorithm>
 #include <atomic>
-#include <string>
 #include <thread>
 
-#include <glog/logging.h>
-
 #include <folly/Likely.h>
 
 namespace folly {