Remove definition of thread annotation macros without RTC_ prefix BUG=webrtc:8198 Review-Url: https://codereview.webrtc.org/3007363002 Cr-Original-Commit-Position: refs/heads/master@{#19810} Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc Cr-Mirrored-Commit: 47791cf0f8400984c0e90229c756e404ba7eee4f