sys/: Removing some useless debugs messages, correctly cleaning the image created to check xshm calls on succes, adde...

Original commit message from CVS:
2004-01-28  Julien MOUTTE <julien@moutte.net>

* sys/ximage/ximagesink.c: (gst_ximagesink_check_xshm_calls),
(gst_ximagesink_ximage_new), (gst_ximagesink_ximage_destroy),
(gst_ximagesink_ximage_put), (gst_ximagesink_xwindow_new),
(gst_ximagesink_xwindow_destroy):
* sys/xvimage/xvimagesink.c: (gst_xvimagesink_check_xshm_calls),
(gst_xvimagesink_xvimage_new), (gst_xvimagesink_xvimage_destroy),
(gst_xvimagesink_xwindow_new), (gst_xvimagesink_xwindow_destroy),
(gst_xvimagesink_xwindow_resize), (gst_xvimagesink_get_xv_support),
(gst_xvimagesink_xcontext_get): Removing some useless debugs messages,
correctly cleaning the image created to check xshm calls on succes,
added a lot of XSync calls in X11 functions, and fixed a segfault when
no image format was defined before negotiation happened.