avformat/vobsub: raise packet even if apparently incomplete.

This restore the latest packet which was dropped from the FATE test in
dbfe6110.

libavformat/mpeg.c

@@ -849,8 +849,11 @@ static int vobsub_read_packet(AVFormatContext *s, AVPacket *pkt)
         int pkt_size;
 
         ret = mpegps_read_pes_header(vobsub->sub_ctx, NULL, &startcode, &pts, &dts);
-        if (ret < 0)
+        if (ret < 0) {
+            if (pkt->size) // raise packet even if incomplete
+                break;
             FAIL(ret);
+        }
         to_read = ret & 0xffff;
         new_pos = avio_tell(pb);
         pkt_size = ret + (new_pos - old_pos);

tests/ref/fate/sub2video

@@ -92,3 +92,4 @@
 1,     210600,     210600,     1831,      665, 0x55580135, F=0x0
 1,     214771,     214771,     1558,     1216, 0x50d1f6c5, F=0x0
 1,     225640,     225640,     2127,     2133, 0x670c11a5, F=0x0
+1,     227834,     227834,     1262,     1264, 0xc1d9fc57, F=0x0