Add copyright headers to remaining gyp files.

gyp/canvas_state_lib.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.
 # Building test for running CanvasState
 
 # HOW TO USE:
 # This target is not included in normal Skia builds. In order to build it,
 # you need to run gyp_skia on this file. This target also requires the
 # variable skia_pic to be used during building:
 #
 # GYP_DEFINES=skia_pic=1 ./gyp_skia gyp/canvas_state_lib.gyp
 # ninja -C out/Debug canvas_state_lib
 #
@@ skipping 17 matching lines @@
     {
         # Dummy 'most' target, since gyp_skia sets 'most' to be the default.
         'target_name' : 'most',
         'type'        : 'none',
         'dependencies' : [
           'canvas_state_lib',
         ],
     }
   ],
 }