Reduce our internal dependence on the Cogl 1.x api

Since Cogl has started restricting what cogl 1.x api is exposed when
COGL_ENABLE_EXPERIMENTAL_2_0_API is defined and since we build all
Clutter internals with COGL_ENABLE_EXPERIMENTAL_2_0_API defined this
patch makes a first pass at reducing our internal use of the Cogl 1.x
api.

The most notable api that's no longer exposed to us internally is
the cogl_material_ api so this switches all Clutter internals to use the
cogl_pipeline_ api instead. This patch also makes quite a bit of
progress removing internal uses of CoglHandle although there is still
more to go.

clutter/clutter-cogl-compat.h

@@ -0,0 +1,52 @@
+/*
+ * Clutter.
+ *
+ * An OpenGL based 'interactive canvas' library.
+ *
+ * Copyright (C) 2012  Intel Corporation.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef __CLUTTER_COGL_COMPAT_H__
+#define __CLUTTER_COGL_COMPAT_H__
+
+#if !defined(__CLUTTER_H_INSIDE__) && !defined(CLUTTER_COMPILATION)
+#error "Only <clutter/clutter.h> can be included directly."
+#endif
+
+G_BEGIN_DECLS
+
+/* XXX: Some public Clutter apis depend on Cogl types that have been
+ * removed from the Cogl 2.0 experimental api.
+ *
+ * If somone has opted to use the Cogl 2.0 experimental api by
+ * defining COGL_ENABLE_EXPERIMENTAL_2_0_API then we need to define
+ * some place holder typdefs for compatability.
+ *
+ * NB: we build all clutter internals with COGL_ENABLE_EXPERIMENTAL_2_0_API
+ * defined.
+ */
+
+#ifdef COGL_ENABLE_EXPERIMENTAL_2_0_API
+
+/* CoglMaterial has been replaced with CoglPipeline in Cogl 2.0 */
+typedef struct _CoglMaterial CoglMaterial;
+
+#endif
+
+G_END_DECLS
+
+#endif /* __CLUTTER_COGL_COMPAT_H__ */