examples/remuxing: Fix use of uninitialized value

Fixes Coverity ticket 1492326.
Regression since 53f374c08d.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

doc/examples/remuxing.c

@@ -68,7 +68,7 @@ int main(int argc, char **argv)
     pkt = av_packet_alloc();
     if (!pkt) {
         fprintf(stderr, "Could not allocate AVPacket\n");
-        goto end;
+        return 1;
     }
 
     if ((ret = avformat_open_input(&ifmt_ctx, in_filename, 0, 0)) < 0) {