avcodec/vp8: Do not use num_coeff_partitions in thread/buffer setup

avcodec/vp8: Do not use num_coeff_partitions in thread/buffer setup

The variable is not a constant and can lead to race conditions

Fixes: repro.webm (not reproducable with FFmpeg alone)
Found-by: Dale Curtis <dalecurtis@google.com>
Tested-by: Dale Curtis <dalecurtis@google.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
Gbp-Pq: Name CVE-2015-6761.patch

disable-configuration-warnings

Gbp-Pq: Name 03-disable-configuration-warnings.patch

configure-disable-ebx-gcc-4.9

Gbp-Pq: Name 02-configure-disable-ebx-gcc-4.9.patch

libav (6:11.12-1~deb8u8) jessie-security; urgency=medium

  * CVE-2019-14442: avformat/mpc8: fix hang with fuzzed file.
  * CVE-2018-5766: lavc/avpacket: Fix undefined behaviour, do not pass a null
    pointer to memcpy().
  * CVE-2019-14372: wvdec: check for eof in wv_read_block_header().
  * CVE-2017-9987: avcodec/mpegvideo_motion: Fix off by 1 error in MV bounds
    checking.
  * CVE-2018-11102:
    - mov_probe: fix integer overflows.
    - mov.c: Check for stsd + m1s tag indicating MOV-wrapped MPEG-PS, and force
      continued probing if found.

[dgit import unpatched libav 6:11.12-1~deb8u8]

Import libav_11.12-1~deb8u8.debian.tar.xz

[dgit import tarball libav 6:11.12-1~deb8u8 libav_11.12-1~deb8u8.debian.tar.xz]

Import libav_11.12.orig.tar.xz

[dgit import orig libav_11.12.orig.tar.xz]