compositor-x11: Set xcb to be eventqueue owner

This'll fix egl_gallium (when bind_wayland_display is done).
diff --git a/compositor/compositor-x11.c b/compositor/compositor-x11.c
index b437337..9e8ce75 100644
--- a/compositor/compositor-x11.c
+++ b/compositor/compositor-x11.c
@@ -651,6 +651,8 @@
 		return NULL;
 
 	c->conn = XGetXCBConnection(c->dpy);
+	XSetEventQueueOwner(c->dpy, XCBOwnsEventQueue);
+
 	if (xcb_connection_has_error(c->conn))
 		return NULL;