Stop using LOG macros in favor of RTC_ prefixed macros.

This CL has been generated with the following script:

for m in PLOG \
  LOG_TAG \
  LOG_GLEM \
  LOG_GLE_EX \
  LOG_GLE \
  LAST_SYSTEM_ERROR \
  LOG_ERRNO_EX \
  LOG_ERRNO \
  LOG_ERR_EX \
  LOG_ERR \
  LOG_V \
  LOG_F \
  LOG_T_F \
  LOG_E \
  LOG_T \
  LOG_CHECK_LEVEL_V \
  LOG_CHECK_LEVEL \
  LOG
do
  git grep -l $m | xargs sed -i "s,\b$m\b,RTC_$m,g"
done
git checkout rtc_base/logging.h
git cl format

Bug: webrtc:8452
Change-Id: I1a53ef3e0a5ef6e244e62b2e012b864914784600
Reviewed-on: https://webrtc-review.googlesource.com/21325
Reviewed-by: Niels Moller <nisse@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20617}
diff --git a/rtc_base/task_queue.h b/rtc_base/task_queue.h
index 7842ea3..2f247e6 100644
--- a/rtc_base/task_queue.h
+++ b/rtc_base/task_queue.h
@@ -119,7 +119,7 @@
 //     }
 //     ...
 //     my_class->StartWorkAndLetMeKnowWhenDone(
-//         NewClosure([]() { LOG(INFO) << "The work is done!";}));
+//         NewClosure([]() { RTC_LOG(INFO) << "The work is done!";}));
 //
 //   3) Posting a custom task on a timer.  The task posts itself again after
 //      every running: