Add gmock into our dependencies.

third_party/boost/boost/mpl/void_fwd.hpp

Index: third_party/boost/boost/mpl/void_fwd.hpp
diff --git a/third_party/boost/boost/mpl/void_fwd.hpp b/third_party/boost/boost/mpl/void_fwd.hpp
new file mode 100644
index 0000000000000000000000000000000000000000..68cace7bcca21148faba53772212d45782cc412e
--- /dev/null
+++ b/third_party/boost/boost/mpl/void_fwd.hpp
@@ -0,0 +1,26 @@
+
+#ifndef BOOST_MPL_VOID_FWD_HPP_INCLUDED
+#define BOOST_MPL_VOID_FWD_HPP_INCLUDED
+
+// Copyright Aleksey Gurtovoy 2001-2004
+//
+// Distributed under the Boost Software License, Version 1.0. 
+// (See accompanying file LICENSE_1_0.txt or copy at 
+// http://www.boost.org/LICENSE_1_0.txt)
+//
+// See http://www.boost.org/libs/mpl for documentation.
+
+// $Source$
+// $Date: 2004-09-02 11:41:37 -0400 (Thu, 02 Sep 2004) $
+// $Revision: 24874 $
+
+#include <boost/mpl/aux_/adl_barrier.hpp>
+
+BOOST_MPL_AUX_ADL_BARRIER_NAMESPACE_OPEN
+
+struct void_;
+
+BOOST_MPL_AUX_ADL_BARRIER_NAMESPACE_CLOSE
+BOOST_MPL_AUX_ADL_BARRIER_DECL(void_)
+
+#endif // BOOST_MPL_VOID_FWD_HPP_INCLUDED