gcc 4.1 unreferenced pointer fixes.

gcc 4.1 unreferenced pointer fixes.

Original commit message from CVS:
* ext/ogg/gstoggdemux.c: (gst_ogg_pad_dispose):
* gst/playback/gstplaybin.c: (handoff):
* gst/playback/gststreamselector.c:
(gst_stream_selector_set_property):
gcc 4.1 unreferenced pointer fixes.
* sys/ximage/ximagesink.c: (gst_ximagesink_ximage_put):
* sys/xvimage/xvimagesink.c: (gst_xvimagesink_xvimage_put):
gst_buffer_ref() now takes a GstBuffer*.