Fix a number of things in AudioEncoderDecoderIsac*

- Add max_bit_rate and max_payload_size_bytes to config structs.
- Fix support for 48 kHz sample rate.
- Fix iSAC-RED.
- Add method UpdateDecoderSampleRate().
- Update locking structure with a separate lock for local member
variables used by the encoder methods.

BUG=3926
COAUTHOR:kwiberg@webrtc.org

R=minyue@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/41659004

Cr-Commit-Position: refs/heads/master@{#8204}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8204 4adac7df-926f-26a2-2b94-8c16560cd09d
5 files changed