Update thread annotiation macros in modules to use RTC_ prefix

BUG=webrtc:8198

Review-Url: https://codereview.webrtc.org/3010223002
Cr-Original-Commit-Position: refs/heads/master@{#19728}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 56359be7fea745a29a47d3a36b99016e6dbd2741