Add copyright headers to remaining gyp files.

gyp/gmslides.gypi

+# Copyright 2015 Google Inc.
+#
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
 # include this gypi to include all the golden master slides.
 {
   'include_dirs': [
     '../gm',
     # include dirs needed by particular GMs
     '../src/utils/debugger',
     '../src/images',
     '../src/lazy',
   ],
   'conditions': [
@@ skipping 247 matching lines @@
         '../gm/shadertext2.cpp',
         '../gm/shadertext3.cpp',
 
         # TODO(reed): Allocates more memory than Android devices are capable of
         # fulfilling. See http://skbug.com/1978
         '../gm/verylargebitmap.cpp',
       ],
     }],
   ],
 }