Add gmock into our dependencies.

third_party/boost/boost/type_traits/has_nothrow_destructor.hpp

Index: third_party/boost/boost/type_traits/has_nothrow_destructor.hpp
diff --git a/third_party/boost/boost/type_traits/has_nothrow_destructor.hpp b/third_party/boost/boost/type_traits/has_nothrow_destructor.hpp
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index 0000000000000000000000000000000000000000..4f5882afc00a4e7152e32b4b38b477384a24a87a
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+++ b/third_party/boost/boost/type_traits/has_nothrow_destructor.hpp
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+
+//  (C) Copyright Steve Cleary, Beman Dawes, Howard Hinnant & John Maddock 2000.
+//  Use, modification and distribution are subject to 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/type_traits for most recent version including documentation.
+
+#ifndef BOOST_TT_HAS_NOTHROW_DESTRUCTOR_HPP_INCLUDED
+#define BOOST_TT_HAS_NOTHROW_DESTRUCTOR_HPP_INCLUDED
+
+#include <boost/type_traits/has_trivial_destructor.hpp>
+
+// should be the last #include
+#include <boost/type_traits/detail/bool_trait_def.hpp>
+
+namespace boost {
+
+BOOST_TT_AUX_BOOL_TRAIT_DEF1(has_nothrow_destructor,T,::boost::has_trivial_destructor<T>::value)
+
+} // namespace boost
+
+#include <boost/type_traits/detail/bool_trait_undef.hpp>
+
+#endif // BOOST_TT_HAS_NOTHROW_DESTRUCTOR_HPP_INCLUDED