adaptive: schedule update against next segment time
adaptive: schedule update against next segment time

avoids stalled playback when playback starts from end
of list.

refs http://rt-a.akamaihd.net/ch_01@325605/480p.m3u8

xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc,xkfz007/vlc