lavc: rewrite and extend AVFrame doxy
lavc: make pkt_{p,d}ts doxy less confusing
huffyuv: split encoder and decoder into separate files.
4xm: don't rely on get_buffer() initializing the frame.
aura: cosmetics, reformat
asvdec: cosmetics, reformat
ansi: remove an extra return
aasc: cosmetics, reformat
8bps: cosmetics

Remove some pointless comments and empty lines.
hlsenc: correctly report target duration
oggdec: K&R cosmetic formatting
oggdec: check memory allocation
configure: cosmetics: Separate hwaccel dependencies from decoders/encoders

Also move mpegvideo_select statement to the correct position.
Return proper error code after av_log_ask_for_sample()
avfilter: Compile FIFO filters unconditionally

Building libavfilter without that functionality makes little sense.
lavc: Correct the description of pkt_dts

The description as updated in 6e5c44b0f made it sound like it is
handled exactly like the pts, which it is not. Clarify that it
is the packet that triggered returning the frame instead of just
the last avpacket (in case of frame threading, it won't be the
dts of the last packet).

Signed-off-by: Martin Storsjö <martin@martin.st>
hlsenc: Allocate enough space for the pattern string

If s->filename doesn't contain any period/filename extension to strip
away, the buffer will be too small to fit both strings. This isn't
any buffer overflow since the concatenation uses av_strlcat with
the right buffer size.

Signed-off-by: Martin Storsjö <martin@martin.st>
hlsenc: Don't duplicate a string constant

Signed-off-by: Martin Storsjö <martin@martin.st>
bmp: cosmetics, reformat
c93: set palette_has_changed.