mjpegdec: properly report unsupported disabled features

When JPEG-LS support is disabled the decoder would feed the
data to the JPEG Lossless decode_*_scan function resulting in
faulty decoding.

CC: libav-stable@libav.org
flacdec: drop unnecessary assert

The condition cannot happen anymore.
sparc: Eliminate dead code in VIS acceleration macros

Signed-off-by: Diego Biurrun <diego@biurrun.de>
vc1dec: Add support for interlaced B-frames

Signed-off-by: Martin Storsjö <martin@martin.st>
movenc: Don't add base_data_offset in tfhd for PIFF files

According to the PIFF specification[1] the base_data_offset field MUST be
omitteed. See section 5.2.17. Since the ISMV files created by libavformat
state that they are 'piff' compatible via 'ftyp' box, this needs to be
corrected.

[1] http://www.iis.net/learn/media/smooth-streaming/protected-interoperable-file-format

Signed-off-by: Martin Storsjö <martin@martin.st>
vc1dec: Fix mv_f shuffling

Avoid a (confusing) memcpy(), making the code simpler code.
Fixes a small number of artifacts in black_screen_VC-1.mkv
and several more artifacts in other videos.
vc1dec: Redesign the intensity compensation

The existing implementation had little to do with VC1.
This could be implemented by adjusting the reference frames
ithemselfs but that would make frame multi-threading difficult.
vc1dec: Implement intensity compensation for vc1_interp_mc()
vc1: Use use_ic instead of shuffling mv_mode around
vc1dec: Drop old use_ic code from vc1_b_mc
vc1dec: Drop mv_f_last, simplify code
vc1dec: Fix doxy for vc1_mc_4mv_chroma4()
vc1dec: Add avg & variable direction support to vc1_mc_4mv_chroma4()
vc1dec: Try to fix vc1_mc_4mv_chroma4() parameters - todo: Squash into previous?

This fixes several chroma artifacts in several videos.

Todo: Should this be squashed into the previous commit, or keep
them separate (where the previous refactors and adds new possible
parameters while this one actually takes them into use)?
vc1dec: Match addressing between compensation and MC in vc1_mc_4mv_chroma4
vc1dec: Fix mixed field/frame intensity compensation

Fixes ffmpeg Ticket2523
vc1dec: Fix lutuv use in vc1_mc_4mv_chroma4()
vc1dec: Remove interlaced warning

Also add a note about the feature in the changelog.
vc1dec: Factorize lut clean code
vc1dec: Make sure next_use_ic is set correctly