[gegl] buffer: fix gegl-tile-source.h when included in C++ files

[Ell <ell src gnome org>]

commit 1770ec6128a84c6f8ec44121947600849c8b682e
Author: Ell <ell_se yahoo com>
Date:   Sat Jun 30 04:54:44 2018 -0400

    buffer: fix gegl-tile-source.h when included in C++ files

 gegl/buffer/gegl-tile-source.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/gegl/buffer/gegl-tile-source.h b/gegl/buffer/gegl-tile-source.h
index dced59945..4fff7a56a 100644
--- a/gegl/buffer/gegl-tile-source.h
+++ b/gegl/buffer/gegl-tile-source.h
@@ -95,8 +95,8 @@ gegl_tile_source_get_tile (GeglTileSource *source,
   GeglTile *tile;
   
 
-  tile = gegl_tile_source_command (source, GEGL_TILE_GET,
-                                   x, y, z, NULL);
+  tile = (GeglTile *) gegl_tile_source_command (source, GEGL_TILE_GET,
+                                                x, y, z, NULL);
 
   return tile;
 }