hlsenc: Add 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: Martin Storsjö <martin@martin.st>
Merge commit '55f03d872640175a00bfa262da4652b7312b905f'

* commit '55f03d872640175a00bfa262da4652b7312b905f':
  hlsenc: Add parameter -hls_allow_cache

Conflicts:
	doc/muxers.texi
	libavformat/hlsenc.c
	libavformat/version.h

See: 3edb9aaea6aaa6b93d708693cfa6454c17e03732
Merged-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/smc: fix off by 1 error

Fixes out of array access
Fixes: asan_heap-oob_1685bf0_5_asan_heap-oob_1f35116_430_smc.mov

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>