Bug 368377. Stop exporting cairo headers from thebes headers.

Fix Solaris compiler bustage.
Patch by Andreas Lange anlan@lange.cx. r=pavlov.

gfx/thebes/src/gfxASurface.cpp

@@ -219,7 +219,7 @@ gfxASurface::MarkDirty(const gfxRect& r)
 void
 gfxASurface::SetData(const cairo_user_data_key_t *key,
                      void *user_data,
-                     cairo_destroy_func_t destroy)
+                     thebes_destroy_func_t destroy)
 {
     cairo_surface_set_user_data(mSurface, key, user_data, destroy);
 }