Update zlib to 1.2.5.

third_party/zlib/zlib.gyp

 # Copyright (c) 2011 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.
 
 {
   'variables': {
     'conditions': [
       [ 'os_posix == 1 and OS != "mac" and OS != "openbsd"', {
         # Link to system .so since we already use it due to GTK.
         # TODO(pvalchev): OpenBSD is purposefully left out, as the system
@@ skipping 53 matching lines @@
               '.',
             ],
           },
           'conditions': [
             ['OS!="win"', {
               'product_name': 'chrome_zlib',
               'sources!': [
                 'contrib/minizip/iowin32.c'
               ],
             }],
+            ['OS=="mac"', {
+              # Mac does not have fopen64, ftello64, or fseeko64. We use fopen,
+              # ftell, and fseek instead on Mac.
+              'defines': [
+                'USE_FILE32API'
+              ],
+            }],
           ],
         },
       ],
     }, {
       'targets': [
         {
           'target_name': 'zlib',
           'type': 'static_library',
           'direct_dependent_settings': {
             'defines': [
@@ skipping 19 matching lines @@
           'link_settings': {
             'libraries': [
               '-lz',
             ],
           },
         },
       ],
     }],
   ],
 }