Update thread annotiation macros to use RTC_ prefix

webrtc/rtc_base/task_queue_win.cc

Index: webrtc/rtc_base/task_queue_win.cc
diff --git a/webrtc/rtc_base/task_queue_win.cc b/webrtc/rtc_base/task_queue_win.cc
index 00a8c79827573b7fde17d894879763430bce5c3c..6ff64c0789c1ab5bd2002babed12fe9bb8fe59a5 100644
--- a/webrtc/rtc_base/task_queue_win.cc
+++ b/webrtc/rtc_base/task_queue_win.cc
@@ -236,7 +236,8 @@ class TaskQueue::Impl : public RefCountInterface {
   TaskQueue* const queue_;
   WorkerThread thread_;
   rtc::CriticalSection pending_lock_;
-  std::queue<std::unique_ptr<QueuedTask>> pending_ GUARDED_BY(pending_lock_);
+  std::queue<std::unique_ptr<QueuedTask>> pending_
+      RTC_GUARDED_BY(pending_lock_);
   HANDLE in_queue_;
 };