[gegl] sampler: clean up some casting warnings

[Michael Henning <mhenning src gnome org>]

commit 351858176007093ed95c925881f8e2d331a305c8
Author: Michael Henning <drawoc darkrefraction com>
Date:   Mon Apr 8 18:14:20 2013 -0400

    sampler: clean up some casting warnings

 gegl/buffer/gegl-sampler.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/gegl/buffer/gegl-sampler.c b/gegl/buffer/gegl-sampler.c
index e686187..6204bf5 100644
--- a/gegl/buffer/gegl-sampler.c
+++ b/gegl/buffer/gegl-sampler.c
@@ -511,13 +511,13 @@ set_buffer (GeglSampler *self, GeglBuffer *buffer)
           g_signal_handlers_disconnect_by_func (self->buffer,
                                                 G_CALLBACK (buffer_contents_changed),
                                                 self);
-          g_object_remove_weak_pointer (self->buffer, &self->buffer);
+          g_object_remove_weak_pointer ((GObject*) self->buffer, (void**) &self->buffer);
         }
 
       if (GEGL_IS_BUFFER (buffer))
         {
           self->buffer = buffer;
-          g_object_add_weak_pointer (self->buffer, &self->buffer);
+          g_object_add_weak_pointer ((GObject*) self->buffer, (void**) &self->buffer);
           g_signal_connect (buffer, "changed",
                             G_CALLBACK (buffer_contents_changed),
                             self);