configure: Enable -Qansi-alias for icl 14+

Qansi-alias worked on 12.x, then caused miscompilation on 13.x, but now
works again passing all FATE tests for icl version 14.

Signed-off-by: Diego Biurrun <diego@biurrun.de>
mpegvideo: Initialize chroma_*_shift and codec_tag even if the size is 0

This fixes breakage in a few fate tests on certain setups
(that for some reason didn't break on OS X) after the previous
commit (8812a8057). Currently, some video streams are initialized
in ff_MPV_common_init with width/height set at 0 and only changed
to a proper video size with ff_MPV_common_frame_size_change later.

The breakage was diagnosed by Anton Khirnov.

Signed-off-by: Martin Storsjö <martin@martin.st>
h264_sei: log unknown sei messages

Signed-off-by: Anton Khirnov <anton@khirnov.net>
h264: log extradata skip only for non-ignored NALs

Signed-off-by: Anton Khirnov <anton@khirnov.net>
h264: do not discard NAL_SEI when skipping frames

Setting AVDISCARD_NONREF (e.g. after flushing) resulted in 100% dropped frames.

Signed-off-by: Anton Khirnov <anton@khirnov.net>
h264_sei: check SEI size

Signed-off-by: Anton Khirnov <anton@khirnov.net>
pixdesc: fix NV20* descriptors

They were inconsistent (overlapping fields and wrong sizes)

Signed-off-by: Anton Khirnov <anton@khirnov.net>
lavc: add support for interleaved chroma formats to libx264.

Interleaved chroma is x264's native format

Signed-off-by: Anton Khirnov <anton@khirnov.net>
matroskadec: check av_strdup() when setting defaults
cabac: remove write-only h264_mps_state[]
h264: do not reinitialize the global cabac tables at each slice header
doc/filters: fix an option name in the unsharp docs
lavc doxy: document that avcodec_flush_buffers() invalidates decoded frames