Fix the bug in m3u8delete, set error deadline for private download link.
Fix the bug in m3u8delete, set error deadline for private download link.

qiniu-lab/qshell,liangchao07115/qshell,liangchao07115/qshell,qiniu-lab/qshell,jemygraw/qshell,qiniu/qshell,jemygraw/qshell