Merge mp3 support from Orphis' old FFMPEG code.

Conflicts:
	CMakeLists.txt
	Core/HLE/sceAudio.cpp
	Core/HLE/sceMp3.cpp
	Core/HLE/sceMpeg.cpp
Uncomment some unused stack-corrupting code from sceMp3Decode. Update ffmpeg.
Fix sceMp3 build without USE_FFMPEG
Fix crash in mp3 reading.
Merge pull request #1786 from unknownbrackets/mp3-support

Fix crash in mp3 reading
Get mp3 sample rate and channels from FFMPEG instead of trying to detect ourselves.
VERBOSE a log statement
Both video/audio timestamp seem to start from firstTimeStamp in sceMpeg.

Fix video playback for Castlevania Dracula X Chronicles.
Merge pull request #2239 from oioitff/patch-1

Both video/audio timestamp seem to start from firstTimeStamp in sceMpeg.
added FFMPEG support in iOS build

Also added a new README with more detailed instructions on compiling
the iOS version
Updated ios-build.sh in ffmpeg submodule
Merge pull request #2241 from jtraynham/master

Added FFMPEG support to iOS build
Implement scePsmfVerifyPsmf
Change to DEBUG_LOG
Merge pull request #2244 from raven02/patch-6

Implement scePsmfVerifyPsmf()
Update ffmpeg.
Correct result of scePsmfGetVideoInfo().
Clean up scePsmf logging.
Clean up scePsmfPlayer logging.

Move a bunch of things from errors.
Re-enable subimage optimization with scaling fix.

Thanks go to @Squall-Leonhart for finding the issue.