GN: Change rtc_source_set targets --> rtc_static_library

webrtc/libjingle/xmllite/BUILD.gn

 # Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 import("../../build/webrtc.gni")
 
 group("xmllite") {
   public_deps = [
     ":rtc_xmllite",
   ]
 }
 
-rtc_source_set("rtc_xmllite") {
+rtc_static_library("rtc_xmllite") {
   sources = [
     "qname.cc",
     "qname.h",
     "xmlbuilder.cc",
     "xmlbuilder.h",
     "xmlconstants.cc",
     "xmlconstants.h",
     "xmlelement.cc",
     "xmlelement.h",
     "xmlnsstack.cc",
@@ skipping 14 matching lines @@
       "//third_party/expat",
     ]
   }
 
   if (!build_with_chromium && is_clang) {
     # Suppress warnings from Chrome's Clang plugins.
     # See http://code.google.com/p/webrtc/issues/detail?id=163 for details.
     suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
   }
 }