xcbgrab: XCB-based screen capture

Matches the x11grab screen capture by features.
matroskaenc: write correct Display{Width, Height} in stereo encoding

should be the raw amount of pixels (for example 3840x1080 for full HD side by
side) and the DisplayWidth/Height in pixels should be the amount of pixels for
one plane (1920x1080 for that full HD stream)."

So, move the aspect ratio check in the mkv_write_stereo_mode() function
and always write the embl when stereo format and/or aspect ration is set.
Also add a few comments to that function.

CC: libav-stable@libav.org
Found-by: Asan Usipov <asan.usipov@gmail.com>
filmstripdec: avoid integer overflow

CC: libav-stable@libav.org
Bug-Id: CID 732246
bethsoftvid: check return value and clean memory

CC: libav-stable@libav.org
Bug-Id: CID 733777
mxfdec: reduce loop bound in mxf_read_pixel_layout()

Makes coverity less confused and code more readable.

Bug-Id: CID 732262
avcodec/sgidec: fix linesize for 16bit

Fixes: asan_heap-oob_22b30d4_39_038.sgi
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/sgidec: fix count check

Fixes: asan_heap-oob_22b30d4_39_038.sgi
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'a6674d2e7771dbf7a4a5556f5e126be83cadac96'

* commit 'a6674d2e7771dbf7a4a5556f5e126be83cadac96':
  xcbgrab: XCB-based screen capture

Conflicts:
	Changelog
	configure
	libavdevice/Makefile
	libavdevice/alldevices.c
	libavdevice/version.h

Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '090c67d586e3916f9acc49e010b6389d07f97153'

* commit '090c67d586e3916f9acc49e010b6389d07f97153':
  matroskaenc: write correct Display{Width, Height} in stereo encoding

Conflicts:
	libavformat/matroskaenc.c

See: 6103faaa51d2f46d6ccecaad9a089b4b42ff66ee
Merged-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'b46b233baffc2076a1a17a264ba9553ae0d4878f'

* commit 'b46b233baffc2076a1a17a264ba9553ae0d4878f':
  filmstripdec: avoid integer overflow

Merged-by: Michael Niedermayer <michaelni@gmx.at>
avformat/filmstripdec: Fix several integer overflows

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit 'e6c66f1e4ea19a3aa6ed999c5cb92e1b682c7600'

* commit 'e6c66f1e4ea19a3aa6ed999c5cb92e1b682c7600':
  bethsoftvid: check return value and clean memory

Conflicts:
	libavformat/bethsoftvid.c

See: 3632f35c8e163f6aa6d63c317e3e1fca6a4a5fab
Merged-by: Michael Niedermayer <michaelni@gmx.at>
avformat/bethsoftvid: print error in case the side date failed to be allocated

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
Merge commit '11467ecf519788f2e2f49c63a17eb600e618489e'

* commit '11467ecf519788f2e2f49c63a17eb600e618489e':
  mxfdec: reduce loop bound in mxf_read_pixel_layout()

See: 187630b2449f1eae1096f81f31bab7d81bed3cf1
Merged-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/diracdec: Use 64bit in calculation of codeblock coordinates

Fixes integer overflow
Fixes out of array read
Fixes: asan_heap-oob_107866c_42_041.drc
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/diracdec: Tighter checks on CODEBLOCKS_X/Y

Fixes very long but finite loop
Fixes: asan_heap-oob_107866c_42_041.drc
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/dirac_arith: fix integer overflow

Fixes: asan_heap-oob_1078676_9_008.drc
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>