Update thread annotiation macros in rtc_base to use RTC_ prefix

webrtc/rtc_base/task_queue.h

Index: webrtc/rtc_base/task_queue.h
diff --git a/webrtc/rtc_base/task_queue.h b/webrtc/rtc_base/task_queue.h
index 966b29c40d0c1dc54fa76b6da509003a27a121e2..64e6a6ca5c3b00b4c64373bbc64b3c7ae2420656 100644
--- a/webrtc/rtc_base/task_queue.h
+++ b/webrtc/rtc_base/task_queue.h
@@ -149,7 +149,7 @@ static std::unique_ptr<QueuedTask> NewClosure(const Closure& closure,
 // TaskQueue itself has been deleted or it may happen synchronously while the
 // TaskQueue instance is being deleted.  This may vary from one OS to the next
 // so assumptions about lifetimes of pending tasks should not be made.
-class LOCKABLE TaskQueue {
+class RTC_LOCKABLE TaskQueue {
  public:
   // TaskQueue priority levels. On some platforms these will map to thread
   // priorities, on others such as Mac and iOS, GCD queue priorities.