Add missing header files to GN files

third_party/freetype/BUILD.gn

 # Copyright 2014 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("//build/config/chromecast_build.gni")
 
 config("freetype_config") {
   include_dirs = [
     "include",
     "src/include",
@@ skipping 10 matching lines @@
   }
 }
 
 component("freetype") {
   if (is_linux) {
     output_name = "freetype"
     output_extension = "so.6"
   }
 
   sources = [
+    "include/freetype-custom-config/ftmodule.h",
+    "include/freetype-custom-config/ftoption.h",
     "src/src/autofit/autofit.c",
     "src/src/base/ftbase.c",
     "src/src/base/ftbbox.c",
     "src/src/base/ftbitmap.c",
     "src/src/base/ftfntfmt.c",
     "src/src/base/ftfstype.c",
     "src/src/base/ftgasp.c",
     "src/src/base/ftglyph.c",
     "src/src/base/ftinit.c",
     "src/src/base/ftlcdfil.c",
@@ skipping 42 matching lines @@
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [ "//build/config/compiler:no_chromium_code" ]
 
   configs += [ ":freetype-warnings" ]
 
   deps = [
     "//third_party/libpng",
     "//third_party/zlib",
   ]
 }