webpmux: Also print compression info per frame.
webpmux: Also print compression info per frame.

As per the user request:
https://groups.google.com/a/webmproject.org/forum/#!topic/webp-discuss/dk9M-q1MFnw

Change-Id: Id2540413a89e1f043e50abb0cec7c69367ee8325

webmproject/libwebp,webmproject/libwebp,PKRoma/libwebp,webmproject/libwebp,PKRoma/libwebp,PKRoma/libwebp,webmproject/libwebp,webmproject/libwebp,PKRoma/libwebp,PKRoma/libwebp,PKRoma/libwebp