Update to use libav version 9.

Update to use libav version 9.

Version 9 has changed the interface in a number of ways.  Sorry about the whitespace change, look at this if you want to just look at my changes:

https://github.com/arichnad/aveasy/commit/4706d06e80a0e6b7397346e63a727d6ad62fd567

http://libav.org/releases/libav-9.11.changelog