Add gmock into our dependencies.

third_party/boost/boost/type_traits/add_cv.hpp

Index: third_party/boost/boost/type_traits/add_cv.hpp
diff --git a/third_party/boost/boost/type_traits/add_cv.hpp b/third_party/boost/boost/type_traits/add_cv.hpp
new file mode 100644
index 0000000000000000000000000000000000000000..bfde76a623f9fc8c4f1f128c6f9968d1b320e985
--- /dev/null
+++ b/third_party/boost/boost/type_traits/add_cv.hpp
@@ -0,0 +1,48 @@
+
+//  (C) Copyright Dave Abrahams, 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_ADD_CV_HPP_INCLUDED
+#define BOOST_TT_ADD_CV_HPP_INCLUDED
+
+#include <boost/config.hpp>
+
+// should be the last #include
+#include <boost/type_traits/detail/type_trait_def.hpp>
+
+namespace boost {
+
+// * convert a type T to a const volatile type - add_cv<T>
+// this is not required since the result is always
+// the same as "T const volatile", but it does suppress warnings
+// from some compilers:
+
+#if defined(BOOST_MSVC)
+// This bogus warning will appear when add_volatile is applied to a
+// const volatile reference because we can't detect const volatile
+// references with MSVC6.
+#   pragma warning(push)
+#   pragma warning(disable:4181) // warning C4181: qualifier applied to reference type ignored
+#endif 
+
+BOOST_TT_AUX_TYPE_TRAIT_DEF1(add_cv,T,T const volatile)
+
+#if defined(BOOST_MSVC)
+#   pragma warning(pop)
+#endif 
+
+#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
+BOOST_TT_AUX_TYPE_TRAIT_PARTIAL_SPEC1_1(typename T,add_cv,T&,T&)
+#endif
+
+} // namespace boost
+
+#include <boost/type_traits/detail/type_trait_undef.hpp>
+
+#endif // BOOST_TT_ADD_CV_HPP_INCLUDED