wmall: use AVFrame API properly

This fixes a bug with non-refcounted callers resulting in invalid memory access.

Signed-off-by: Anton Khirnov <anton@khirnov.net>
Merge remote-tracking branch 'qatar/master'

* qatar/master:
  wmall: use AVFrame API properly

Conflicts:
	libavcodec/wmalosslessdec.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
lavfi/trim: check for right default value

Signed-off-by: Paul B Mahol <onemda@gmail.com>
ffmpeg_filter: do not pick evil path for trim filters

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