Update thread annotiation macros in rtc_base to use RTC_ prefix

webrtc/rtc_base/fakeclock.h

 /*
  *  Copyright 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 24 matching lines @@
   void SetTimeMicros(int64_t micros) {
     SetTimeNanos(kNumNanosecsPerMicrosec * micros);
   }
 
   void AdvanceTime(TimeDelta delta);
   void AdvanceTimeMicros(int64_t micros) {
     AdvanceTime(rtc::TimeDelta::FromMicroseconds(micros));
   }
  private:
   CriticalSection lock_;
-  int64_t time_ GUARDED_BY(lock_) = 0;
+  int64_t time_ RTC_GUARDED_BY(lock_) = 0;
 };
 
 // Helper class that sets itself as the global clock in its constructor and
 // unsets it in its destructor.
 class ScopedFakeClock : public FakeClock {
  public:
   ScopedFakeClock();
   ~ScopedFakeClock() override;
 
  private:
   ClockInterface* prev_clock_;
 };
 
 // Helper class to "undo" the fake clock temporarily.
 class ScopedRealClock {
  public:
   ScopedRealClock();
   ~ScopedRealClock();
 
  private:
   ClockInterface* prev_clock_;
 };
 
 }  // namespace rtc
 
 #endif  // WEBRTC_RTC_BASE_FAKECLOCK_H_