Add xmllite and xmpp sources to third_party/

third_party/libjingle_xmpp/xmllite/xmlconstants.h

+/*
+ *  Copyright 2004 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.
+ */
+
+#ifndef WEBRTC_LIBJINGLE_XMLLITE_XMLCONSTANTS_H_
+#define WEBRTC_LIBJINGLE_XMLLITE_XMLCONSTANTS_H_
+
+#include "third_party/libjingle_xmpp/xmllite/qname.h"
+
+namespace buzz {
+
+extern const char STR_EMPTY[];
+extern const char NS_XML[];
+extern const char NS_XMLNS[];
+extern const char STR_XMLNS[];
+extern const char STR_XML[];
+extern const char STR_VERSION[];
+extern const char STR_ENCODING[];
+
+extern const StaticQName QN_XMLNS;
+
+}  // namespace buzz
+
+#endif  // WEBRTC_LIBJINGLE_XMLLITE_XMLCONSTANTS_H_