ext/: GstObjects must be unref'ed with gst_object_unref() instead of g_object_unref(), otherwise things break for GLi...

Original commit message from CVS:
* ext/ivorbis/vorbisfile.c: (gst_ivorbisfile_loop):
* ext/libmms/gstmms.c: (gst_mms_src_query), (gst_mms_create):
* ext/musepack/gstmusepackdec.c: (gst_musepackdec_src_query),
(gst_musepackdec_loop):
* ext/swfdec/gstswfdec.c: (gst_swfdec_video_link),
(gst_swfdec_src_query):
* ext/wavpack/gstwavpackparse.c: (gst_wavpack_parse_src_query):
GstObjects must be unref'ed with gst_object_unref() instead of
g_object_unref(), otherwise things break for GLib-2.6 users.