avformat/hlsenc: hls_init_time should used in living stream mode

When hls_init_time should available when hls_list_size > 0.
Because the list will not refresh new top line segment when hls_list_size is 0
Signed-off-by: Steven Liu <lq@chinaffmpeg.org>

libavformat/hlsenc.c

@@ -2947,7 +2947,7 @@ static int hls_init(AVFormatContext *s)
         av_log(hls, AV_LOG_DEBUG, "start_number evaluated to %"PRId64"\n", hls->start_sequence);
     }
 
-    hls->recording_time = hls->init_time ? hls->init_time : hls->time;
+    hls->recording_time = hls->init_time && hls->max_nb_segments > 0 ? hls->init_time : hls->time;
 
     if (hls->flags & HLS_SPLIT_BY_TIME && hls->flags & HLS_INDEPENDENT_SEGMENTS) {
         // Independent segments cannot be guaranteed when splitting by time