Support compat with old generated PB files

include/grpc++/impl/codegen/config.h

@@ -39,6 +39,12 @@
 #define GRPC_CUSTOM_STRING std::string
 #endif
 
+// The following macros are deprecated and appear only for users
+// with PB files generated using gRPC 1.0.x plugins. They should
+// not be used in new code
+#define GRPC_OVERRIDE override  // deprecated
+#define GRPC_FINAL final        // deprecated
+
 namespace grpc {
 
 typedef GRPC_CUSTOM_STRING string;