sceMpegRingbufferAvailableSize might use a different

Based on http://code.google.com/p/jpcsp/source/detail?r=1813
Fix #5112
Merge pull request #6641 from sum2012/mpeg-minor

sceMpegRingbufferAvailableSize might use a different ringbuffer than sceMpegCreate. Use the new one.
Merge pull request #6640 from JimLee168/master

Atrac buffer validate RIFF header
x86 JIT: Fix bug where NOR would not get computed correctly in corner case

(CompTriArith can end up not actually mapping rd to a register when taking
a shortcut)

May fix the JIT issue mentioned by CPkmn and located by daniel229 as an aside in #6638
x86 jit: Further fix for nor, thanks unknown

See #6638
Fix crash after loading state from within Psmf movie

(a variable was not initialized)
Merge pull request #1 from hrydgard/master

Update from original