Add gmock into our dependencies.

third_party/boost/boost/type_traits/detail/template_arity_spec.hpp

Index: third_party/boost/boost/type_traits/detail/template_arity_spec.hpp
diff --git a/third_party/boost/boost/type_traits/detail/template_arity_spec.hpp b/third_party/boost/boost/type_traits/detail/template_arity_spec.hpp
new file mode 100644
index 0000000000000000000000000000000000000000..fe9b422e830bffc4259fccbbb113d09b02f6d0ba
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+++ b/third_party/boost/boost/type_traits/detail/template_arity_spec.hpp
@@ -0,0 +1,31 @@
+
+// NO INCLUDE GUARDS, THE HEADER IS INTENDED FOR MULTIPLE INCLUSION
+
+// Copyright Aleksey Gurtovoy 2002-2004
+//
+// 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)
+
+#include <boost/mpl/int.hpp>
+#include <boost/mpl/aux_/template_arity_fwd.hpp>
+#include <boost/mpl/aux_/preprocessor/params.hpp>
+#include <boost/mpl/aux_/config/lambda.hpp>
+#include <boost/mpl/aux_/config/overload_resolution.hpp>
+
+#if defined(BOOST_MPL_CFG_NO_FULL_LAMBDA_SUPPORT) \
+    && defined(BOOST_MPL_CFG_BROKEN_OVERLOAD_RESOLUTION)
+#   define BOOST_TT_AUX_TEMPLATE_ARITY_SPEC(i, name) \
+namespace mpl { namespace aux { \
+template< BOOST_MPL_PP_PARAMS(i, typename T) > \
+struct template_arity< \
+          name< BOOST_MPL_PP_PARAMS(i, T) > \
+        > \
+    : int_<i> \
+{ \
+}; \
+}} \
+/**/
+#else
+#   define BOOST_TT_AUX_TEMPLATE_ARITY_SPEC(i, name) /**/
+#endif