GN: Add -Wl,-z defs on linux and fix errors

media/cast/BUILD.gn

 # 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.
 
 component("cast") {
   deps = [
     ":sender",
     ":receiver",
   ]
 }
@@ skipping 34 matching lines @@
     "logging/stats_event_subscriber.h",
   ]
 
   public_deps = [
     "//media/cast/logging/proto",
   ]
   deps = [
     "//base",
     "//crypto",
     "//net",
+    "//third_party/zlib",
   ]
 }
 
 source_set("net") {
   sources = [
     "net/cast_transport_config.cc",
     "net/cast_transport_config.h",
     "net/cast_transport_defines.h",
     "net/cast_transport_sender.h",
     "net/cast_transport_sender_impl.cc",
@@ skipping 299 matching lines @@
   sources = [
     "test/utility/udp_proxy_main.cc",
   ]
 
   deps = [
     ":test_support",
     "//base",
     "//net",
   ]
 }