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/pc/externalhmac.cc b/pc/externalhmac.cc
index 91f7412..348b33b 100644
--- a/pc/externalhmac.cc
+++ b/pc/externalhmac.cc
@@ -141,8 +141,8 @@
   srtp_err_status_t status = srtp_replace_auth_type(
       const_cast<srtp_auth_type_t*>(&external_hmac), EXTERNAL_HMAC_SHA1);
   if (status) {
-    LOG(LS_ERROR) << "Error in replacing default auth module, error: "
-                  << status;
+    RTC_LOG(LS_ERROR) << "Error in replacing default auth module, error: "
+                      << status;
     return srtp_err_status_fail;
   }
   return srtp_err_status_ok;