gst/realmedia/rmdemux.c: For version 4 streams, read the extra codec data size from...

gst/realmedia/rmdemux.c: For version 4 streams, read the extra codec data size from the header instead of assuming it...

Original commit message from CVS:
Based on patch by: Roland Kay  <roland.kay at ox compsoc net>
* gst/realmedia/rmdemux.c: (gst_rmdemux_parse_mdpr):
For version 4 streams, read the extra codec data size from the
header instead of assuming it is always 16 (also read it from the
right position) (#384989). For version 4 and 5 streams, check that
the specified extra codec data size doesn't make us read beyond the
chunk boundary (#384989).