Add missing header files to GN files

gpu/khronos_glcts_support/BUILD.gn

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//testing/test.gni")
 
 declare_args() {
   internal_khronos_glcts_tests = false
 }
 
@@ skipping 940 matching lines @@
     if (is_linux) {
       configs -= [ "//build/config/gcc:no_exceptions" ]
     }
   }
 }
 
 if (!is_android) {
   test("khronos_glcts_test") {
     sources = [
       "khronos_glcts_test.cc",
+      "khronos_glcts_test.h",
     ]
 
     deps = [
       "//base",
       "//gpu",
       "//testing/gtest",
     ]
 
     data = [
       "khronos_glcts_test_expectations.txt",
     ]
 
     if (internal_khronos_glcts_tests) {
       sources += [ "$target_gen_dir/khronos_glcts_test_autogen.cc" ]
       deps += [
         ":generate_khronos_glcts_tests",
         ":khronos_glcts_test_windowless",
       ]
     }
   }
 }