Remove VIDEOCODEC_* from engine_configurations.h.

Removes index-based codec fetching from the VCM and overall cleans up
the code.

BUG=webrtc:1695
R=mflodman@webrtc.org

Review URL: https://codereview.webrtc.org/1425613004 .

Cr-Original-Commit-Position: refs/heads/master@{#10770}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 92f8dbde77f859449a2b9ac107bca6c9b4329897
8 files changed