avconv: make -shortest work with streamcopy

CC: libav-stable@libav.org
avfilter/avf_showcqt: add option for lower resolution

Resolution can be 1920x1080 or 960x540.
Merge commit '48e50921337984ba4ec2c1cafe45d43787f84498'

* commit '48e50921337984ba4ec2c1cafe45d43787f84498':
  avconv: make -shortest work with streamcopy

Conflicts:
	ffmpeg.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
libx265: Actually use X265_API_IMPORTS

It obvously needs to be above the include statement.

Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
libx265: Add 4:2:2 support

It is also not final yet, so require -strict experimental.

Requires a bump to version 17.

Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
libx265: Remove unneeded bit depth check

This is no longer needed since the version bump.

Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>