spicy: Add call of gst_deinit at program exit
spicy: Add call of gst_deinit at program exit

This is useful for some instrumentation, e.g. the leaks tracer,
that perform some of their operations within gst_deinit.

Without this patch, if you run spicy with
	GST_DEBUG="GST_TRACER:7" GST_TRACERS="leaks" spicy ...
the leak tracer does not show any output, because it runs in gst_deinit.

Signed-off-by: Christophe de Dinechin <e3d13d45b866407e72234c83bf86018df4b2ef13@redhat.com>
Reviewed-by: Marc-André Lureau <a6f2b960a4aca61381fc650a67901b2ac8e83e6d@redhat.com>
Acked-by: Frediano Ziglio <55d48b080b2e443e395cde84d2c83b135a4ff48e@redhat.com>

flexVDI/spice-gtk,flexVDI/spice-gtk