Support for custom NM/readelf binaries in your toolchain.

test/make_global_settings/full-toolchain/make_global_settings.gyp

 # Copyright (c) 2013 Google Inc. All rights reserved.
 # Use of this source code is governed by a BSD-style licence that can be
 # found in the LICENSE file.
 
 {
   'make_global_settings': [
-    ['CC', 'clang'],
-    ['LINK', 'clang'],
+    ['CC', '/bin/echo MY_CC'],
+    ['CXX', '/bin/echo MY_CXX'],
+    ['NM', 'my_nm.py'],
+    ['READELF', 'my_readelf.py'],
   ],
   'targets': [
     {
       'target_name': 'test',
-      'type': 'static_library',
-      'sources': [ 'foo.c' ],
+      'type': 'shared_library',
+      'sources': [
+        'foo.c',
+        'bar.cc',
+      ],
     },
   ],
 }