mpegvideo: move the MpegEncContext fields used from arm asm to the beginning

This should reduce the frequency with which the offsets need to be
updated.
mpegvideo: remove unused MpegEncContext.b4_stride
h264: drop commented out cruft
avconv_dxva2: define all used GUIDs directly instead of relying on the dxva2api.h header

This avoids issues with inconsistent headers with different versions of mingw-w64 and older MSVC variants.

Fixes FATE builds of MSVC 2010.

Signed-off-by: Anton Khirnov <anton@khirnov.net>
Merge commit '6a13505c069890cb0e2a07e29fd819a0cf2e73c1'

* commit '6a13505c069890cb0e2a07e29fd819a0cf2e73c1':
  mpegvideo: move the MpegEncContext fields used from arm asm to the beginning

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'c1f92d13589d431e576d719dd44427486a5e05cd'

* commit 'c1f92d13589d431e576d719dd44427486a5e05cd':
  mpegvideo: remove unused MpegEncContext.b4_stride

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '9d76dd952ffd9fffc7f9fb5cc5af6d093ba54521'

* commit '9d76dd952ffd9fffc7f9fb5cc5af6d093ba54521':
  h264: drop commented out cruft

Conflicts:
	libavcodec/h264_slice.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'a7c5fddac8137654cb503295c4dfb6492df43643'

* commit 'a7c5fddac8137654cb503295c4dfb6492df43643':
  avconv_dxva2: define all used GUIDs directly instead of relying on the dxva2api.h header

Merged-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/vorbisdec: try to workaround libvorbisenc bug

Fixes Ticket3590

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/vorbisdec: use av_malloc(z)_array()

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>