when total.m3u8 is new,set total duration to 0

@@ -867,6 +867,7 @@ int SrsHlsMuxer::segment_close(string log_desc)
 
 				srs_verbose("write m3u8 header success.");
 				m3u8_total_endlist_saved = false;
+				this->total_duraion = 0;
 			}