Redirect logs to stderr in audioproc_f.

Notably, this displays logs from the AGC.

Also add a "time per chunk" field to the perf output.

R=aluebs@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/56509004

Cr-Commit-Position: refs/heads/master@{#9302}
2 files changed