[gegl] Simplify gegl_buffer_set_extent

[Daniel Sabo <daniels src gnome org>]

commit 3d007cebaf12451af19dc57882fa07ec6bda6ed4
Author: Daniel Sabo <DanielSabo gmail com>
Date:   Tue Oct 8 05:06:11 2013 -0700

    Simplify gegl_buffer_set_extent

 gegl/buffer/gegl-buffer.c |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)
---
diff --git a/gegl/buffer/gegl-buffer.c b/gegl/buffer/gegl-buffer.c
index 16c04e7..53b12c2 100644
--- a/gegl/buffer/gegl-buffer.c
+++ b/gegl/buffer/gegl-buffer.c
@@ -331,14 +331,16 @@ gboolean
 gegl_buffer_set_extent (GeglBuffer          *buffer,
                         const GeglRectangle *extent)
 {
+  GeglBufferHeader *header;
+
   g_return_val_if_fail (GEGL_IS_BUFFER (buffer), FALSE);
 
-  (*(GeglRectangle*) gegl_buffer_get_extent (buffer)) = *extent;
+  buffer->extent = *extent;
+
+  header = gegl_buffer_backend (buffer)->priv->header;
 
-  if ((GeglBufferHeader*)(gegl_buffer_backend (buffer)->priv->header))
+  if (header)
     {
-      GeglBufferHeader *header =
-        ((GeglBufferHeader*)(gegl_buffer_backend (buffer)->priv->header));
       header->x = buffer->extent.x;
       header->y = buffer->extent.y;
       header->width = buffer->extent.width;