[gnome-builder] libide/tweaks: add missing include guard

[Christian Hergert <chergert src gnome org>]

commit 4e8f27a5117629bd09323f2029cfea78e3708e15
Author: Christian Hergert <chergert redhat com>
Date:   Fri Aug 12 15:42:01 2022 -0700

    libide/tweaks: add missing include guard

 src/libide/tweaks/ide-tweaks-widget.h | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/src/libide/tweaks/ide-tweaks-widget.h b/src/libide/tweaks/ide-tweaks-widget.h
index ec1725d8a..3f9e39c66 100644
--- a/src/libide/tweaks/ide-tweaks-widget.h
+++ b/src/libide/tweaks/ide-tweaks-widget.h
@@ -20,6 +20,10 @@
 
 #pragma once
 
+#if !defined (IDE_TWEAKS_INSIDE) && !defined (IDE_TWEAKS_COMPILATION)
+# error "Only <libide-tweaks.h> can be included directly."
+#endif
+
 #include <gtk/gtk.h>
 
 #include "ide-tweaks-item.h"