cache: fix seek when skipping data
cache: fix seek when skipping data

AStreamReadNoSeekStream can return a value less than the length argument
without failing.

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