Add version-specific defines for each C interface.

ppapi/c/ppb_instance.h

 /* Copyright (c) 2010 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #ifndef PPAPI_C_PPB_INSTANCE_H_
 #define PPAPI_C_PPB_INSTANCE_H_
 
 #include "ppapi/c/pp_bool.h"
 #include "ppapi/c/pp_instance.h"
 #include "ppapi/c/pp_resource.h"
 #include "ppapi/c/pp_var.h"
 
-#define PPB_INSTANCE_INTERFACE "PPB_Instance;0.4"
+#define PPB_INSTANCE_INTERFACE_0_4 "PPB_Instance;0.4"
+#define PPB_INSTANCE_INTERFACE PPB_INSTANCE_INTERFACE_0_4
 
 /**
  * @file
  * This file defines the PPB_Instance interface implemented by the
  * browser and containing pointers to functions related to
  * the module instance on a web page.
  *
  * @addtogroup Interfaces
  * @{
  */
@@ skipping 83 matching lines @@
   struct PP_Var (*ExecuteScript)(PP_Instance instance,
                                  struct PP_Var script,
                                  struct PP_Var* exception);
 };
 /**
  * @}
  */
 
 #endif  /* PPAPI_C_PPB_INSTANCE_H_ */