Reason for revert:
This CL breaks the google3 import (but not the import bot).
This partial revert only reverts the build files. A full revert no longer cleanly applies to ToT, so this was done instead.
Original issue's description:
> Enable -Winconsistent-missing-override flag.
>
> The problem with gmock is worked around by commenting out any other override declarations in classes using gmock.
>
> NOPRESUBMIT=True
> BUG=webrtc:3970
>
> Committed: https://crrev.com/ef8b61e11062295365f11b9942f18a08a8b3ec60
> Cr-Commit-Position: refs/heads/master@{#12563}
TBR=mflodman@webrtc.org,kjellander@webrtc.org,nisse@webrtc.org
BUG=webrtc:3970
Review-Url: https://codereview.webrtc.org/1944273002
Cr-Commit-Position: refs/heads/master@{#12624}
053f917741