lavf: Only initialize s->offset once when using avoid_negative_ts make_zero

When given a stream starting at dts=0, it would previously consider
s->offset as uninitialized and set an offset when the second packet
was written, ending up writing two packets with dts=0. By initializing
this field to AV_NOPTS_VALUE, we make sure that we only initialize it
once, on the first packet.

Signed-off-by: Martin Storsjö <martin@martin.st>
librtmp: append the correct field to the string

Also prevent a NULL pointer dereference.

CC: libav-stable@libav.org
Bug-Id: CID 1250329 / CID 1250331
libvpxenc: clean memory on error

CC: libav-stable@libav.org
Bug-Id: CID 733795
lavc: fix bitshifts amount bigger than the type

CC: libav-stable@libav.org
Bug-Id: CID 1194387 / CID 1194389 / CID 1194393 / CID 1206638
mov: check ff_get_wav_header() return value

CC: libav-stable@libav.org
Bug-Id: CID 717497
configure: Fix enabling memalign_hack automatically

simd_align_16 is a configure item that can be enabled or disabled,
it's not a variable containing a list of other configure items
as need_memalign previously. This was broken in eba2233b5.

CC: libav-stable@libav.org
Signed-off-by: Martin Storsjö <martin@martin.st>
hdsenc: Use the right filename in an error message

Signed-off-by: Martin Storsjö <martin@martin.st>
hdsenc: Clear the previous codec tag when setting up the chained muxer

The chained flv muxer wants one set of tags - normally this set
could be signaled via the AVOutputFormat codec_tag field (as
smoothstreamingenc and dashenc do). hdsenc doesn't signal it, since
the FLV codec tag arrays aren't exported from flvenc.c. This can
lead to the caller keeping an original codec tag from the originating
container here, which would then be a mismatch for the FLV muxer.
Since we don't really care about what codec tag the caller might
have set, just clear it and let the lavf muxer layer set the right
one for the chained FLV muxer later instead.

Signed-off-by: Martin Storsjö <martin@martin.st>