movenc: allow alternative hvc1 h.265 codec tag

If AVCodecParameters.codec_tag is 'hvc1' use it instead of 'hev1' for
h.265 streams. QuickTime (and other Apple software) requires 'hvc1'.

(cherry picked from commit 84ab1cc4)
Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>