lavfi/aresample: raise filter_frame() error.
lavfi/asetnsamples: raise filter_frame() error.
lavfi/atempo: raise filter_frame() error.
lavfi/aevalsrc: raise filter_frame() error.
lavfi/anullsrc: raise filter_frame() error.
lavfi/concat: raise filter_frame() error.
lavfi/avfilter: raise filter_frame() error.
lavfi/showspectrum: raise filter_frame() error.
lavfi/buffersrc: raise filter_frame() error.
lavfi/movie: raise filter_frame() error.
lavfi/alphamerge: raise filter_frame() error.
lavfi/cellauto: raise filter_frame() error.
lavfi/life: raise filter_frame() error.
lavfi/mandelbrot: raise filter_frame() error.
lavfi/mptestsrc: raise filter_frame() error.
lavfi/thumbnail: remove unecessary poll_frame() callback.
lavc: factorize ff_{thread_,re,}get_buffer error messages.

Coccinelle profile used:

  @@
  expression r, ctx, f, loglevel, str, flags;
  @@

  -if ((r = ff_get_buffer(ctx, f, flags)) < 0) {
  -    av_log(ctx, loglevel, str);
  -    return r;
  -}
  +if ((r = ff_get_buffer(ctx, f, flags)) < 0)
  +    return r;

  @@
  expression r, ctx, f, loglevel, str;
  @@

  -if ((r = ff_reget_buffer(ctx, f)) < 0) {
  -    av_log(ctx, loglevel, str);
  -    return r;
  -}
  +if ((r = ff_reget_buffer(ctx, f)) < 0)
  +    return r;

  @@
  expression r, ctx, f, loglevel, str, flags;
  @@

  -if ((r = ff_thread_get_buffer(ctx, f, flags)) < 0) {
  -    av_log(ctx, loglevel, str);
  -    return r;
  -}
  +if ((r = ff_thread_get_buffer(ctx, f, flags)) < 0)
  +    return r;

...along with some manual patches for the remaining ones.
lavc/crystalhd: remove now unecessary buffer_hints.
lavfi/delogo: remove sscanf and rely on av_opt_set_from_string() only.
avcodec: remove AVCodecContext->metadata

This field was only ever set and freed from avcodec, and not otherwise
used. However, because frames are refcounted now, avcodec cannot make any
assumptions about the lifetime of the frame metadata, which can result in
double-frees or leaked memory.

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