Add copyright headers to remaining gyp files.

gyp/gputest.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': 'skgputest',
       'product_name': 'skia_skgputest',
       'type': 'static_library',
       'standalone_static_library': 1,
       'dependencies': [
         'skia_lib.gyp:skia_lib',
       ],
@@ skipping 10 matching lines @@
       },
       'sources': [
         '<(skia_src_path)/gpu/GrContextFactory.cpp',
         '<(skia_src_path)/gpu/GrContextFactory.h',
         '<(skia_src_path)/gpu/GrTest.cpp',
         '<(skia_src_path)/gpu/GrTest.h',
       ],
     },
   ],
 }