Remove -Wno-unused-private-field clang warning suppression.

third_party/hunspell/hunspell.gyp

 # Copyright (c) 2009 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': 'hunspell',
       'type': 'static_library',
       'msvs_guid': 'D5E8DCB2-9C61-446F-8BEE-B18CA0E0936E',
@@ skipping 52 matching lines @@
           'USE_HUNSPELL',
         ],
       },
       'variables': {
         'clang_warning_flags': [
           # affentry.cxx has one `while ((p = nextchar(p)));` parsing loop.
           '-Wno-empty-body',
           # affentry.hxx has NULL as default parameter for a FLAG in two
           # places.
           '-Wno-null-conversion',
+          # hunspell has unused private fields.
+          '-Wno-unused-private-field',
         ],
       },
       # TODO(jschuh): http://crbug.com/167187 size_t -> int
       'msvs_disabled_warnings': [ 4267 ],
       'conditions': [
         ['os_posix == 1 and OS != "mac"', {
           'cflags': [
             '-Wno-unused-value',
             '-Wno-unused-variable',
             '-Wno-write-strings',
           ],
         }],
         ['gcc_version >= 48', {
           'cflags': [
             # affentry.hxx has NULL as default parameter for a FLAG in two
             # places.
             '-Wno-conversion-null',
           ],
         }],
       ],
     },
   ],
 }