[3.6.x] x-callback-url: URL-decode sub parameter
Requested here: https://forum.videolan.org/viewtopic.php?f=36&t=166347
(cherry picked from commit e67766cd, back-port of !1498 (merged))
Requested here: https://forum.videolan.org/viewtopic.php?f=36&t=166347
(cherry picked from commit e67766cd, back-port of !1498 (merged))
VideoLAN code repository instance