Add gmock into our dependencies.

third_party/boost/boost/fusion/container/generation/ignore.hpp

Index: third_party/boost/boost/fusion/container/generation/ignore.hpp
diff --git a/third_party/boost/boost/fusion/container/generation/ignore.hpp b/third_party/boost/boost/fusion/container/generation/ignore.hpp
new file mode 100644
index 0000000000000000000000000000000000000000..6a416c6b5cba1213c4fe68122e9de52c5499818e
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+++ b/third_party/boost/boost/fusion/container/generation/ignore.hpp
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+/*=============================================================================
+    Copyright (c) 2001 Doug Gregor
+    Copyright (c) 1999-2003 Jaakko Jarvi
+    Copyright (c) 2001-2006 Joel de Guzman
+
+    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)
+==============================================================================*/
+#if !defined(FUSION_IGNORE_07192005_0329)
+#define FUSION_IGNORE_07192005_0329
+
+namespace boost { namespace fusion
+{
+    //  Swallows any assignment (by Doug Gregor)
+    namespace detail
+    {
+        struct swallow_assign
+        {
+            template<typename T>
+            swallow_assign const&
+            operator=(const T&) const
+            {
+                return *this;
+            }
+        };
+    }
+
+    //  "ignore" allows tuple positions to be ignored when using "tie".
+    detail::swallow_assign const ignore = detail::swallow_assign();
+}}
+
+#endif