Update flatbuffers to HEAD of upstream

third_party/flatbuffers/flatbuffers.gyp

 # 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.
 
 {
   'targets': [
     {
       'target_name': 'compiler_files',
       'type': 'static_library',
       'include_dirs': [
         'src/include',
       ],
       'sources': [
         'src/src/idl_gen_cpp.cpp',
         'src/src/idl_gen_fbs.cpp',
         'src/src/idl_gen_general.cpp',
         'src/src/idl_gen_go.cpp',
         'src/src/idl_gen_js.cpp',
         'src/src/idl_gen_php.cpp',
         'src/src/idl_gen_python.cpp',
         'src/src/idl_gen_text.cpp',
         'src/src/idl_parser.cpp',
         'src/src/reflection.cpp',
         'src/src/util.cpp',
-        'src/include/idl.h',
-        'src/include/util.h',
+        'src/include/flatbuffers/code_generators.h',
+        'src/include/flatbuffers/idl.h',
+        'src/include/flatbuffers/util.h',
       ],
     },
     {
       'target_name': 'flatbuffers',
       'type': 'static_library',
       'include_dirs': [
         'src/include',
       ],
       'direct_dependent_settings': {
         'include_dirs': [
@@ skipping 51 matching lines @@
         # but are listed here because test.cpp tests more than
         # what will get included into Chrome (reflection and generation).
         'src/include/reflection_generated.h',
         'src/include/reflection.h',
         # This is the actual test.
         'src/tests/test.cpp',
       ]
     }
   ],
 }