Revert "codecparsers: remove ignored increment of return"

This reverts commit 916b954315.

Clearly something else was intended, and it also makes
more sense to add the extra bit. The resync marker is
N zero bits plus a 1 bit, and the pattern/mask needs to
be run on N+1 bits too.

(Even after the rever the code doesn't do that of course, so
it still needs to be fixed differently.)

https://bugzilla.gnome.org/show_bug.cgi?id=739345

gst-libs/gst/codecparsers/gstmpeg4parser.c

@@ -347,7 +347,7 @@ compute_resync_marker_size (const GstMpeg4VideoObjectPlane * vop,
     }
   }
 
-  return off;
+  return off++;                 /* Take the following 1 into account */
 }
 
 /**