Some filters need several input frames before producing output.
For these filter, it becomes simpler to return 0 in
request_frame() and let the framework call it again until
output has been produced.

* cehoyos/master:
  Fix make checkheaders without opencl headers.
Merged-by: Michael Niedermayer <michaelni@gmx.at>

* qatar/master:
  avfiltergraph: check for sws opts being non-NULL before using them.

Conflicts:
	libavfilter/avfiltergraph.c
	libavfilter/graphparser.c
Merged-by: Michael Niedermayer <michaelni@gmx.at>

* commit '817dff57':
  configure: Check for the atomic.h functions used in the suncc atomics header

Conflicts:
	configure
Merged-by: Michael Niedermayer <michaelni@gmx.at>

Regression since a93b572a.

Fixes #2426.
Signed-off-by: Paul B Mahol <onemda@gmail.com>

* commit 'f9f6402e':
  configure: prettify atomics handling.

Conflicts:
	configure
Merged-by: Michael Niedermayer <michaelni@gmx.at>

Signed-off-by: Paul B Mahol <onemda@gmail.com>

Fixes #1884.
Signed-off-by: Paul B Mahol <onemda@gmail.com>

Fixes compilation with clang on netbsd with --disable-optimizations.

Tested-by: Paul B Mahol

Signed-off-by: Paul B Mahol <onemda@gmail.com>

Avoid snprintfing a NULL pointer.

CC: libav-stable@libav.org

The "suncc" atomics implementation uses a suncc specific memory
barrier, but also relies on a few atomic functions from atomic.h,
that are not suncc specific but specific to solaris. This made
the current implementation fail on suncc on linux.

Add simpler names and a shorthand for native atomics (as opposed to
pthreads fallback).

Fixes Seeking with the file in Ticket2283
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

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

Fixes Ticket2236
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

Fixes Ticket2211
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

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

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

Signed-off-by: Paul B Mahol <onemda@gmail.com>

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

Fixes Ticket2383
Reviewed-by: Marton Balint <cus@passwd.hu>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

Split long lines, reindent code, add missing spaces between operators,
remove possibly confusing comment from av_opencl_buffer_read_image()
doxy, and use designated initializers for openclutils_class.

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

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

* cigaes/master:
  lavfi/af_asetnsamples: fix EOF handling.
  lavu/opt: make sure av_opt_set_bin() handles NULL/0.
  lavd/v4l2: fully init an ioctl argument.
  lavfi: detect merge failure for unknown layouts.
Merged-by: Michael Niedermayer <michaelni@gmx.at>

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

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

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

* qatar/master:
  oma: Validate sample rates

Conflicts:
	libavformat/oma.c

See: a30165c4Merged-by: Michael Niedermayer <michaelni@gmx.at>

Only filter one buffered frame.
Correctly return EOF if there is none.

Silence a valgrind warning about uninitialized memory.