Update ffmpeg
Update ffmpeg for DTS fix
Check the decoder exists before trying to decode
(CCCP Patch) CCCP LAV Filters' defaults.

Enable the mixer for now, as Lord had problems with
the Windows one. Maybe with NT6 we'll all be able to
disable this without thinking too much about it :V

Also enable the LAV Splitter's tray icon for testing for now.
(CCCP Patch) Enable some additional things in ffmpeg

Also contains extra stuff to make both build scripts work locally
(CCCP Patch) Make LAV Video prefer YV12 to NV12 on XP
[MPC-HC] Tray icon: Add an optional custom callback for "show property page" events.