ape: Don't allow the seektable to be omitted

The seektable is required for filling in ape->frames[i].pos
further down.

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
Signed-off-by: Martin Storsjö <martin@martin.st>

libavformat/ape.c

@@ -260,7 +260,7 @@ static int ape_read_header(AVFormatContext * s)
                ape->totalframes);
         return -1;
     }
-    if (ape->seektablelength && (ape->seektablelength / sizeof(*ape->seektable)) < ape->totalframes) {
+    if (ape->seektablelength / sizeof(*ape->seektable) < ape->totalframes) {
         av_log(s, AV_LOG_ERROR,
                "Number of seek entries is less than number of frames: %zu vs. %"PRIu32"\n",
                ape->seektablelength / sizeof(*ape->seektable), ape->totalframes);