Add SSL support to the GN build

tools/gn/secondary/third_party/nss/BUILD.gn

 # Copyright (c) 2013 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.
 
 import("//build/config/linux/pkg_config.gni")
 
-# On Linux we always use the system NSS except for SSL.
 if (is_linux) {
-  pkg_config("nss_linux_config") {
+  # This is a dependency on NSS with no libssl. On Linux we use a built-in SSL
+  # library but the system NSS libraries. Non-Linux platforms using NSS use the
+  # hermetic one in //third_party/nss.
+  #
+  # Generally you should depend on //crypto:platform instead of using this
+  # config since that will properly pick up NSS or OpenSSL depending on
+  # platform and build config.
+  pkg_config("system_nss_no_ssl_config") {
     packages = [ "nss" ]
+    extra_args = [ "-v", "-lssl3" ]
   }
 }
+