Update several clang warnings after r287092.

third_party/harfbuzz-ng/harfbuzz.gyp

 # Copyright (c) 2012 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.
 
 {
   'includes': [
     '../../build/win_precompile.gypi',
   ],
   'variables': {
     'variables': {
@@ skipping 127 matching lines @@
             'src',
           ],
           'direct_dependent_settings': {
             'include_dirs': [
               'src',
             ],
           },
           'dependencies': [
             '../../third_party/icu/icu.gyp:icuuc',
           ],
+          'variables': {
+            'clang_warning_flags': [ '-Wno-unused-value', ],
+          },
           'conditions': [
-            ['clang==1', {
-              'xcode_settings': {
-                'WARNING_CFLAGS': [
-                  '-Wno-unused-value',
-                ],
-              },
-              'cflags': [
-                '-Wno-unused-value',
-              ]
-            }],
             ['OS=="win"', {
               # TODO(eae): C4267 on amd64. size_t -> int, size_t -> unsigned int
               'msvs_disabled_warnings': [4267, 4334],
             }],
             ['OS=="mac"', {
               'defines': [
                 'HAVE_CORETEXT',
               ],
               'sources': [
                 'src/hb-coretext.cc',
@@ skipping 22 matching lines @@
             ],
             'libraries': [
               '<!@(<(pkg-config) --libs-only-l harfbuzz)',
             ],
           },
         },
       ],
     }],
   ],
 }