Add audio_coding module OWNERS file.

It should simplify things to have an
OWNERS file at the top level of audio_coding, in addition
to the lower ones.

R=tina.legrand@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/39149004

Cr-Original-Commit-Position: refs/heads/master@{#8373}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 0f7f161ed600cd8f3615a9ed79a97c138472161d
2 files changed