Update thread annotiation macros in rtc_base to use RTC_ prefix

webrtc/rtc_base/bufferqueue.h

Index: webrtc/rtc_base/bufferqueue.h
diff --git a/webrtc/rtc_base/bufferqueue.h b/webrtc/rtc_base/bufferqueue.h
index 3abb8cfa6a1f765ea3ea9e54be8a577ac766bf6b..82f1ac1a18b9ebd2659c1ffee067cfe73d700397 100644
--- a/webrtc/rtc_base/bufferqueue.h
+++ b/webrtc/rtc_base/bufferqueue.h
@@ -50,8 +50,8 @@ class BufferQueue {
   size_t capacity_;
   size_t default_size_;
   CriticalSection crit_;
-  std::deque<Buffer*> queue_ GUARDED_BY(crit_);
-  std::vector<Buffer*> free_list_ GUARDED_BY(crit_);
+  std::deque<Buffer*> queue_ RTC_GUARDED_BY(crit_);
+  std::vector<Buffer*> free_list_ RTC_GUARDED_BY(crit_);
 
   RTC_DISALLOW_COPY_AND_ASSIGN(BufferQueue);
 };