Move UBSan warnings from a blacklist to the source

This is done to make UBSan testing more convenient in integration with projects using WebRTC

Some blacklist entries were obsolete so don't need a replacement

Also fix one of the warnings (thanks, kwiberg@)

BUG=webrtc:8189, webrtc:5486, webrtc:5491

Cr-Original-Commit-Position: refs/heads/master@{#19682}
Cr-Mirrored-Commit: 8ad0e589e7ec1bbb126d118b551c7bda7a9de278
10 files changed