Adds win_x64_dbg to the default trybot set. Replaces win_compile_dbg with win_dbg. This is to cover 32 bit and 64 bit debug configuration in the default trybot set. BUG=webrtc:6178 NOTRY=True Review-Url: https://codereview.webrtc.org/2219763002 Cr-Commit-Position: refs/heads/master@{#13651}