avformat/assdec: output ASS packets

After this the order from the original file is stored through readorder
when doing ffmpeg -i input.ass -c copy output.mkv.

And now that the ASS muxer honors the ReadOrder, extracting the ass back
(without transcoding) restores the original order.
avformat/assdec: make sure "Comments:" events end up in the header
avformat/assdec: reindent after previous commit
avformat/assdec: add myself to Copyright
avformat/assenc: mux an event header if none are found in extradata
avformat/assdec: make sure to free allocated data in case of error
avcodec/microdvddec: remove old compat code
avcodec/subviewerdec: remove old compat code
configure: Provide a safe default for unknonw libcs

Support musl out of box.

Amend commit 9d2cee52d37c7340f85a5d41110282aac03e6855 that got
wrongly merged in its stead.
Merge commit '551746680462538bb5ad7adf55fb1248190428ec'

* commit '551746680462538bb5ad7adf55fb1248190428ec':
  configure: Provide a safe default for unknonw libcs

Conflicts:
	configure

This is not merged as it does not work with musl here, while
our previous solution does.

See: 170e2fd7c39c430b334ea80a1e4dfb10c6fd1e95
Merged-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/ac3enc_template: fix out of array read

Found-by: Andreas Cadhalpun
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
lavd/avfoundation: Add basic PCM audio support.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avformat/hlsenc: Added parameter -hls_allow_cache

The -hls_allow_cache parameter enables explicitly setting the
EXT-X-ALLOW-CACHE tag in the manifest file. That tag indicates
whether the client MAY or MUST NOT cache downloaded media
segments for later replay.

Valid values are 1 (=YES) or 0 (=NO) and the EXT-X-ALLOW-CACHE
will not show in the manifest for other values (or if
-hls_allow_cache is not used.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/libx264: mark unchanged pointer arguments as const

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/libx265: enable psnr reporting when requested by the user

This is similar to what is done in libx264.c

Fixes Ticket3567

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
configure: add noexecstack to linker options if supported.

Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>
Support raw dvdsub palette as stored on normal dvd's

This is how the palette is stored on dvd's. Currently
only xbmc passes the palette information to libavcodec
this way.
Check return value of avio_seek and avoid modifying state if it fails

The code still modifies state if the timestamp is not found. Not
sure exactly how to avoid that.
asf hacks
if av_read_packet returns AVERROR_IO, we are done. ffmpeg's codecs might or might not handle returning any completed demuxed packets correctly