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>