Add copyright headers to remaining gyp files.

gyp/dm.gyp

+# Copyright 2015 Google Inc.
+#
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
 # GYP for "dm" (Diamond Master, a.k.a Dungeon master, a.k.a GM 2).
 {
     'includes': [ 'apptype_console.gypi' ],
 
     'targets': [{
         'target_name': 'dm',
         'type': 'executable',
         'includes': [
           'dm.gypi',
         ],
@@ skipping 13 matching lines @@
               'sources': [
                 '../dm/DMSrcSinkAndroid.cpp',
               ],
               'dependencies': [
                 'utils.gyp:android_utils',
               ],
           }],
         ],
     }]
 }