Get iOS GN build working again

ios/third_party/gcdwebserver/BUILD.gn

 # Copyright 2015 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.
 
 config("public_config") {
   libs = [
     "CFNetwork.framework",
     "MobileCoreServices.framework",
     "z",
   ]
 
   include_dirs = [
     "src/GCDWebServer/Core",
     "src/GCDWebServer/Requests",
     "src/GCDWebServer/Responses",
   ]
 }
 
 config("internal_config") {
   visibility = [ ":gcdwebserver" ]
+
+  # TODO(crbug.com/569158): Suppresses warnings that are treated as errors
+  # when minimum iOS version support is increased to iOS 9 and up.
+  # This should be removed once all deprecation violations have been fixed.
+  cflags = [ "-Wno-deprecated-declarations" ]
   cflags_objc = [ "-fobjc-arc" ]
 }
 
 source_set("gcdwebserver") {
   testonly = true
 
   sources = [
     "src/GCDWebServer/Core/GCDWebServer.h",
     "src/GCDWebServer/Core/GCDWebServer.m",
     "src/GCDWebServer/Core/GCDWebServerConnection.h",
@@ skipping 20 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",
   ]
 
   public_configs = [ ":public_config" ]
   configs += [ ":internal_config" ]
 }