BaseTools: Ecc: Use SPDX in AutoGen Template

The ANTLR autogen files are currently created
without an SPDX identifer. Add the BSD-2-Clause-Patent
ID.

While here, correct the command to do the autogeneration
by using the right filename.

Signed-off-by: Oliver Smith-Denny <osde@microsoft.com>

Author: os-d

BaseTools/Source/Python/Ecc/CParser4/C.g4

@@ -18,18 +18,10 @@ options {
 #
 # THIS FILE IS AUTO-GENENERATED. PLEASE DON NOT MODIFY THIS FILE.
 # This file is generated by running:
-# java org.antlr.Tool C.g
+# java org.antlr.Tool C.g4
 #
 # Copyright (c) 2009 - 2010, Intel Corporation  All rights reserved.
-#
-# This program and the accompanying materials are licensed and made available
-# under the terms and conditions of the BSD License which accompanies this
-# distribution.  The full text of the license may be found at:
-#   http://opensource.org/licenses/bsd-license.php
-#
-# THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
-# WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
-#
+# SPDX-License-Identifier: BSD-2-Clause-Patent
 ##
 
 import Ecc.CodeFragment as CodeFragment