fate: Split fate-pixdesc tests and dispatch them through Make

This allows running all the tests individually and/or in parallel.
ppc: idctdsp: Immediately return if no AltiVec is available

This is how all the other init functions operate.
idct: Split off Xvid IDCT

The Xvid IDCT is only required to decode some Xvid-encoded MPEG-4 files,
so there is no point in having it as an unconditional part of idctdsp.
pngenc: Drop pointless pointer cast in png_write_row()
tscc: Eliminate pointless variable indirections in decode_frame()
Revert "vf_interlace: deprecate lowpass option"

This reverts commit 35b05c5184fb3aa1191e2d1e7f1cae1e11f344a4.
A warning is introduced in case this option is used.
pngdec: correctly indent macros
pixdesc: K&R formatting cosmetics

Also change some comments to multiline.

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>
h264: prevent theoretical infinite loop in SEI parsing

Properly address CVE-2011-3946 and parse bitstream as described in the spec.

CC: libav-stable@libav.org
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Merge commit '706208ef47bffd525c982975d2756f7b2b220b8d'

* commit '706208ef47bffd525c982975d2756f7b2b220b8d':
  fate: Split fate-pixdesc tests and dispatch them through Make

Conflicts:
	tests/fate-run.sh
	tests/ref/fate/filter-pixdesc

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '03c9f357a4c2307a7913cea2cbf0ba817e80beb6'

* commit '03c9f357a4c2307a7913cea2cbf0ba817e80beb6':
  ppc: idctdsp: Immediately return if no AltiVec is available

Conflicts:
	libavcodec/ppc/idctdsp.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'a786c8259dafeca9744252230b5d78f67810770c'

* commit 'a786c8259dafeca9744252230b5d78f67810770c':
  idct: Split off Xvid IDCT

Conflicts:
	libavcodec/Makefile
	libavcodec/mpeg4videodec.c
	libavcodec/x86/Makefile
	libavcodec/x86/idctdsp_init.c

This split is somewhat restructured leaving the xvid IDCT available
outside mpeg4 if manually selected.

The code also could not be merged unchanged as it conflicted with a
bugfix in FFmpeg

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '5735552f1f17ea01dcbc99b08f54b5bf52176a8f'

* commit '5735552f1f17ea01dcbc99b08f54b5bf52176a8f':
  pngenc: Drop pointless pointer cast in png_write_row()

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '4da8cdbb91ddbac118b79076cad4dc28ba72e86f'

* commit '4da8cdbb91ddbac118b79076cad4dc28ba72e86f':
  tscc: Eliminate pointless variable indirections in decode_frame()

Conflicts:
	libavcodec/tscc.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '52269f48e835a52023656f8330262ae70e6061c4'

* commit '52269f48e835a52023656f8330262ae70e6061c4':
  Revert "vf_interlace: deprecate lowpass option"

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '92a36a6b3338df5f5cff573a486e182005367c24'

* commit '92a36a6b3338df5f5cff573a486e182005367c24':
  pngdec: correctly indent macros

Conflicts:
	libavcodec/pngdec.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'b2e059a1ffbdaaa985c6a7dcdd684fa034725238'

* commit 'b2e059a1ffbdaaa985c6a7dcdd684fa034725238':
  pixdesc: K&R formatting cosmetics

Conflicts:
	libavutil/pixdesc.c
	libavutil/pixdesc.h

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '7ab551f9fd9a63586649a7df8790ddaeac55420f'

* commit '7ab551f9fd9a63586649a7df8790ddaeac55420f':
  h264: prevent theoretical infinite loop in SEI parsing

Conflicts:
	libavcodec/h264_sei.c

Not merged, as this would remove 2 bitstream compliance checks.
The specification does not allow the bitstream to end in the middle
of these variable length elements and we have no samples which
have such non compliant truncation either so its better to error
out. Which is simpler as well

This issue also has been fixed long ago
See: 9decfc17bb76da34734296048d390b176abf404c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
h264_mp4toannexb_bsf: rename first_idr to new_idr

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