sys/ximage/ximagesink.c: Optimize images creation for both elements. We don't create...

sys/ximage/ximagesink.c: Optimize images creation for both elements. We don't create the image on caps nego or renego...

Original commit message from CVS:
2004-07-21  Julien MOUTTE  <julien@moutte.net>

* sys/ximage/ximagesink.c: (gst_ximagesink_ximage_new),
(gst_ximagesink_renegotiate_size), (gst_ximagesink_sink_link),
(gst_ximagesink_chain), (gst_ximagesink_set_xwindow_id): Optimize
images creation for both elements. We don't create the image on caps
nego or renego, we just destroy the internal one if present if it does
not match the needs. The chain function takes care of creating a new
image when needed.
* sys/xvimage/xvimagesink.c: (gst_xvimagesink_xvimage_new),
(gst_xvimagesink_xwindow_decorate), (gst_xvimagesink_sink_link),
(gst_xvimagesink_chain), (gst_xvimagesink_buffer_alloc),
(gst_xvimagesink_set_xwindow_id): Additionally xvimage now contains
the image format information. The buffer pool checks for the context
image format and discard images with different formats.
* sys/xvimage/xvimagesink.h: Adding im_format in the xvimage structure.