(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
(CCCP Patch) Make splitting force'able via a setting
(CCCP Patch) Stuff to make both build scripts work locally
(CCCP Patch) Cherry-pick two patches on top of nev's ffmpeg

Namely 06a43baecd2c and 710cd0fddf39 from original ffmpeg

These fix infinite parsing of a file.