motion_est: convert stride to ptrdiff_t

CC: libav-stable@libav.org
Bug-Id: CID 700556 / CID 700557 / CID 700558
mpegenc: prevent a NULL pointer dereference

CC: libav-stable@libav.org
Bug-Id: CID 29261
lavu: move internal define to the only places where it is used
aacdec: avoid an out-of-bounds write

Also move the check in the case it is actually used.

CC: libav-stable@libav.org
Bug-Id: CID 1087090
sol: simplify sol_codec_id()

Bug-Id: CID 1238993
cook: Make sure there is enough extradata

At least 8 bytes are needed (Mono audio).

Bug-Id: CID 741418
CC: libav-stable@libav.org
tiffenc: initialize return value

'ret' can only be used without initialization if s->height <= 0, which can
only happen if avctx->height <= 0, which is validated elsewhere. Doesn't hurt
to still initialize it though.

CC: libav-stable@libav.org
Bug-Id: CID 732296
roqaudio: Always use the frame buffer on flush

Prevent NULL dereference.

CC: libav-stable@libav.org
Bug-Id: CID 703669
Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>
aacsbr: always initialize max_qmf_subbands

Fixes a wordly warning from clang -Wsometimes-uninitialized.