Introduce '--no-duplicate-basename-check' option to disable the check of duplicate basenames

test/same-source-file-name/src/double-static.gyp

 # Copyright (c) 2012 Google Inc. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'targets': [
     {
       'target_name': 'lib',
+      'product_name': 'test_static_lib',
       'type': 'static_library',
       'sources': [
         'prog1.c',
         'func.c',
         'subdir1/func.c',
         'subdir2/func.c',
       ],
       'defines': [
         'PROG="prog1"',
       ],
     },
   ],
 }