Add copyright headers to remaining gyp files.

gyp/xps.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.
 {
   'targets': [
     {
       'target_name': 'xps',
       'product_name': 'skia_xps',
       'type': 'static_library',
       'standalone_static_library': 1,
       'conditions': [
         [ 'skia_os == "win"', {
           'defines': [ 'SK_XPS_USE_DETERMINISTIC_IDS', ],
@@ skipping 27 matching lines @@
             ],
           },
         },{ #else if 'skia_os != "win"'
           'sources': [ '../src/doc/SkDocument_XPS_None.cpp', ],
           'dependencies': [ 'skia_lib.gyp:skia_lib', ],
         }],
       ],
     },
   ],
 }