Unconditionally build VP9 support.

Broken for PeerConnection either way (since VP9 support is announced)
and would fail on a CHECK apart from generating incorrect
offers/answers. This isn't a flag that we want to support, so it's
better to remove the foot-shooting gun.

BUG=
R=asapersson@webrtc.org, kjellander@webrtc.org, phoglund@webrtc.org, stefan@webrtc.org

Review URL: https://codereview.webrtc.org/1451663002 .

Cr-Original-Commit-Position: refs/heads/master@{#10676}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: bd05f0ba52be050d7b438d5e191b8976506018d2
5 files changed