Correct iOS device build for latest Xcode beta.

ios/third_party/gcdwebserver/gcdwebserver.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' : 'gcdwebserver',
       'type': 'static_library',
       'include_dirs': [
         'src/GCDWebServer/Core',
@@ skipping 37 matching lines @@
         'src/GCDWebServer/Responses/GCDWebServerErrorResponse.m',
         'src/GCDWebServer/Responses/GCDWebServerFileResponse.h',
         'src/GCDWebServer/Responses/GCDWebServerFileResponse.m',
         'src/GCDWebServer/Responses/GCDWebServerStreamedResponse.h',
         'src/GCDWebServer/Responses/GCDWebServerStreamedResponse.m',
       ],
       'link_settings': {
         'libraries': [
           '$(SDKROOT)/System/Library/Frameworks/CFNetwork.framework',
           '$(SDKROOT)/System/Library/Frameworks/MobileCoreServices.framework',
-          '$(SDKROOT)/usr/lib/libz.dylib',
         ],
+        'xcode_settings': {
+          'OTHER_LDFLAGS': [
+            '-lz',
+          ]
+        },
       },
     },
   ],
 }