compositor: first destroy backend routines and then display

I caught this when an evdev device fd was trying to trigger the main event
loop, which was already free'd and causing an invalid read.

Signed-off-by: Tiago Vignatti <tiago.vignatti@intel.com>

compositor/compositor.c

@@ -2092,9 +2092,9 @@ int main(int argc, char *argv[])
 
 	if (ec->has_bind_display)
 		ec->unbind_display(ec->display, display);
-	wl_display_destroy(display);
 
 	ec->destroy(ec);
+	wl_display_destroy(display);
 
 	return 0;
 }