vda_h264_dec: remove check_format

Since this function cannot work anymore, this patch simply removes it.
Merge branch 'master' of https://github.com/upsuper/ffmpeg-vdadec

* 'master' of https://github.com/upsuper/ffmpeg-vdadec:
  vda_h264_dec: remove check_format

Merged-by: Michael Niedermayer <michaelni@gmx.at>
flacdec: use init_get_bits8()

Signed-off-by: Paul B Mahol <onemda@gmail.com>
audio frame multi-threaded decoding

Signed-off-by: Paul B Mahol <onemda@gmail.com>
takdec: frame multi-threading support

Signed-off-by: Paul B Mahol <onemda@gmail.com>
flacdec: frame multi-threading support

Signed-off-by: Paul B Mahol <onemda@gmail.com>
ttadec: frame multi-threading support

Signed-off-by: Paul B Mahol <onemda@gmail.com>
wavpack: frame multi-threading support

Signed-off-by: Paul B Mahol <onemda@gmail.com>
alac: frame multi-threading support

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