Update ffmpeg
Separate ATRAC series from Real Audio

ATRAC is not a Real format, although its older versions are at
times seen muxed in Real files.
Add support for ATRAC3+
Use a dispatcher table to lookup YUV->RGB conversion functions.
Initialize some additional fields
Fix YUV->RGB with >8 bit formats
Update ffmpeg
Update center mix level for recent changes in libavresample
Update ffmpeg for ogg duration fix

Fixes issue 418.
Move multithreading out of the template function to reduce binary size.
RGB conversion coefficients are constant.
Add timer.h high-precision timer for profiling
Optimization pass over pixconv functionality
Target stride is constant
Update ffmpeg for VC-1 DXVA2 fix.
[MPC-HC] Use our own ffmpeg clone repository.

WARNING: This should be the first custom commit in our fork and its title should not be modified.
[MPC-HC] LAV Splitter: Exhibits MKV attachments through IDSMResourceBag interface.
[MPC-HC] Tray icon: Add an optional custom callback for "show property page" events.
[MPC-HC] Fix the include directories for FFmpeg's out-of-source-tree build.
[MPC-HC] Version number: Add a "git describe based" commit number to identify the vanilla LAV Filters we are based on.

This way if we distribute LAV Filters version X.Y.Z.N, it means that our custom build is based on:
 - the stable version X.Y.Z,
 - with N official patches (which will be part of next official LAV Filters build),
 - and some custom non-official patches which are here to improve the integration in MPC-HC.