Add gmock into our dependencies.

third_party/boost/boost/preprocessor/debug/error.hpp

Index: third_party/boost/boost/preprocessor/debug/error.hpp
diff --git a/third_party/boost/boost/preprocessor/debug/error.hpp b/third_party/boost/boost/preprocessor/debug/error.hpp
new file mode 100644
index 0000000000000000000000000000000000000000..c8ae5e750566fa13862aecd4b6372835aa32283e
--- /dev/null
+++ b/third_party/boost/boost/preprocessor/debug/error.hpp
@@ -0,0 +1,33 @@
+# /* **************************************************************************
+#  *                                                                          *
+#  *     (C) Copyright Paul Mensonides 2002.
+#  *     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 for most recent version. */
+#
+# ifndef BOOST_PREPROCESSOR_DEBUG_ERROR_HPP
+# define BOOST_PREPROCESSOR_DEBUG_ERROR_HPP
+#
+# include <boost/preprocessor/cat.hpp>
+# include <boost/preprocessor/config/config.hpp>
+#
+# /* BOOST_PP_ERROR */
+#
+# if BOOST_PP_CONFIG_ERRORS
+#    define BOOST_PP_ERROR(code) BOOST_PP_CAT(BOOST_PP_ERROR_, code)
+# endif
+#
+# define BOOST_PP_ERROR_0x0000 BOOST_PP_ERROR(0x0000, BOOST_PP_INDEX_OUT_OF_BOUNDS)
+# define BOOST_PP_ERROR_0x0001 BOOST_PP_ERROR(0x0001, BOOST_PP_WHILE_OVERFLOW)
+# define BOOST_PP_ERROR_0x0002 BOOST_PP_ERROR(0x0002, BOOST_PP_FOR_OVERFLOW)
+# define BOOST_PP_ERROR_0x0003 BOOST_PP_ERROR(0x0003, BOOST_PP_REPEAT_OVERFLOW)
+# define BOOST_PP_ERROR_0x0004 BOOST_PP_ERROR(0x0004, BOOST_PP_LIST_FOLD_OVERFLOW)
+# define BOOST_PP_ERROR_0x0005 BOOST_PP_ERROR(0x0005, BOOST_PP_SEQ_FOLD_OVERFLOW)
+# define BOOST_PP_ERROR_0x0006 BOOST_PP_ERROR(0x0006, BOOST_PP_ARITHMETIC_OVERFLOW)
+# define BOOST_PP_ERROR_0x0007 BOOST_PP_ERROR(0x0007, BOOST_PP_DIVISION_BY_ZERO)
+#
+# endif