window: rename enum pointer_type to cursor_type

This avoids confusion with the pointer devices (struct wl_pointer).
diff --git a/clients/terminal.c b/clients/terminal.c
index c7300e6..32648dd 100644
--- a/clients/terminal.c
+++ b/clients/terminal.c
@@ -2245,7 +2245,7 @@
 		widget_schedule_redraw(widget);
 	}
 
-	return POINTER_IBEAM;
+	return CURSOR_IBEAM;
 }
 
 static struct terminal *