fa_video: Remove dead code
fa_http: Correctly report that file does not support seeking if server does not respond to range requests

Fixes #2154
fa_http: Remove support for HEAD requests in file access

We don't use that anymore
Prefer audio tracks with most channels

Fixes #2155
Pull libav forward

    aacdec: Reset configuration when ADTS channel layout changes

Fixes #2153
hls: Remove filtering on low resolution videos

refs #2153
Don't set stream duration if it's not known

refs #2154
Improve track skipping on non-seekable media players

We now cancel the stream to make event processing faster for
skip_backward event

Fixes #2139