Fix for compiler warnings and deprecated functions usage in videoplayer.

Deprecated functions were:

- AVCodecContext::get_buffer
- AVCodecContext::release_buffer

Changed to:
AVCodecContext::get_buffer2 and setting AVCodecContext::refcounted_frames to 1
before call to avcodec_open2().

release_buffer usage was removed.

Also changed places when some fileds were compared to AV_NOPTS_VALUE
- it's signed, so removed unsigned int casting, or changed casting
to signed int.

Signed-off-by: Lukasz Gromanowski <lgromanowski@gmail.com>
Fix for compiler warnings and deprecated functions usage in videoplayer.

Added ifdefs because changes in API were introduced in libavc 56.1
and this code doesn't compile with older versions (ie. on Ubuntu, or Debian).

Signed-off-by: Lukasz Gromanowski <lgromanowski@gmail.com>
Removed a warning about comparision between signed and unsigned variable in ffmpeg_decoder.

Corrected ifdef from previous commit around codecCtx->refcounted_frames = 1;

Signed-off-by: Lukasz Gromanowski <lgromanowski@gmail.com>
Merge remote-tracking branch 'lgro/videoplayer'