hlsdemux: Reload the variant playlist if refreshing a playlist or downloading a fragm...

hlsdemux: Reload the variant playlist if refreshing a playlist or downloading a fragment fails

This can happen if the playlists have moved due to the variant playlist
now being redirected to another target. This currently only works as long
as the referenced playlists don't change in relation to the variant
playlist, and the new location is purely due to a new path triggered by a
new redirection target of the variant playlist, or a new redirection
target of the playlist itself.

https://bugzilla.gnome.org/show_bug.cgi?id=731164