[gtk] texture: Fix compilation by avoiding to include not-yet available headers

[Rico Tzschichholz <ricotz src gnome org>]

commit 4642e86284c6ffb074eff0bf21daa1b2621e04ce
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Sun Mar 18 20:52:46 2018 +0100

    texture: Fix compilation by avoiding to include not-yet available headers

 gdk/gdktexture.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)
---
diff --git a/gdk/gdktexture.c b/gdk/gdktexture.c
index c2557c4280..d9f8d6fd48 100644
--- a/gdk/gdktexture.c
+++ b/gdk/gdktexture.c
@@ -39,9 +39,17 @@
 #include "gdkinternals.h"
 #include "gdkmemorytextureprivate.h"
 #include "gdkpaintable.h"
+#include "gdksnapshot.h"
 
-#define GTK_COMPILATION
-#include "gtk/gtksnapshot.h"
+#include <graphene.h>
+
+/* HACK: So we don't need to include any (not-yet-created) GSK or GTK headers */
+void
+gtk_snapshot_append_texture (GdkSnapshot            *snapshot,
+                             GdkTexture             *texture,
+                             const graphene_rect_t  *bounds,
+                             const char             *name,
+                             ...) G_GNUC_PRINTF (4, 5);
 
 /**
  * SECTION:gdktexture