gralloc: add padding to alloc_device_t and hwc_composer_device_t

also adds version #defines

Change-Id: I89f19fc7811ea9c9efb579a9f6abb4c3d9011bbf
diff --git a/include/hardware/hwcomposer.h b/include/hardware/hwcomposer.h
index fdf2f59..c72d466 100644
--- a/include/hardware/hwcomposer.h
+++ b/include/hardware/hwcomposer.h
@@ -27,6 +27,9 @@
 __BEGIN_DECLS
 
 /*****************************************************************************/
+
+#define HWC_API_VERSION 1
+
 /**
  * The id of this module
  */
@@ -276,6 +279,8 @@
                 hwc_surface_t sur,
                 hwc_layer_list_t* list);
 
+    void* reserved_proc[8];
+
 } hwc_composer_device_t;