Add gmock into our dependencies.

third_party/boost/boost/config/requires_threads.hpp

Index: third_party/boost/boost/config/requires_threads.hpp
diff --git a/third_party/boost/boost/config/requires_threads.hpp b/third_party/boost/boost/config/requires_threads.hpp
new file mode 100644
index 0000000000000000000000000000000000000000..cfaff23027cd024d5b14d3ab34cf6e70aec3577e
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+++ b/third_party/boost/boost/config/requires_threads.hpp
@@ -0,0 +1,92 @@
+//  (C) Copyright John Maddock 2003. 
+//  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)
+
+
+#ifndef BOOST_CONFIG_REQUIRES_THREADS_HPP
+#define BOOST_CONFIG_REQUIRES_THREADS_HPP
+
+#ifndef BOOST_CONFIG_HPP
+#  include <boost/config.hpp>
+#endif
+
+#if defined(BOOST_DISABLE_THREADS)
+
+//
+// special case to handle versions of gcc which don't currently support threads:
+//
+#if defined(__GNUC__) && ((__GNUC__ < 3) || (__GNUC_MINOR__ <= 3) || !defined(BOOST_STRICT_CONFIG))
+//
+// this is checked up to gcc 3.3:
+//
+#if defined(__sgi) || defined(__hpux)
+#  error "Multi-threaded programs are not supported by gcc on HPUX or Irix (last checked with gcc 3.3)"
+#endif
+
+#endif
+
+#  error "Threading support unavaliable: it has been explicitly disabled with BOOST_DISABLE_THREADS"
+
+#elif !defined(BOOST_HAS_THREADS)
+
+# if defined __COMO__
+//  Comeau C++
+#   error "Compiler threading support is not turned on. Please set the correct command line options for threading: -D_MT (Windows) or -D_REENTRANT (Unix)"
+
+#elif defined(__INTEL_COMPILER) || defined(__ICL) || defined(__ICC) || defined(__ECC)
+//  Intel
+#ifdef _WIN32
+#  error "Compiler threading support is not turned on. Please set the correct command line options for threading: either /MT /MTd /MD or /MDd"
+#else
+#   error "Compiler threading support is not turned on. Please set the correct command line options for threading: -openmp"
+#endif
+
+# elif defined __GNUC__
+//  GNU C++:
+#   error "Compiler threading support is not turned on. Please set the correct command line options for threading: -pthread (Linux), -pthreads (Solaris) or -mthreads (Mingw32)"
+
+#elif defined __sgi
+//  SGI MIPSpro C++
+#   error "Compiler threading support is not turned on. Please set the correct command line options for threading: -D_SGI_MP_SOURCE"
+
+#elif defined __DECCXX
+//  Compaq Tru64 Unix cxx
+#   error "Compiler threading support is not turned on. Please set the correct command line options for threading: -pthread"
+
+#elif defined __BORLANDC__
+//  Borland
+#   error "Compiler threading support is not turned on. Please set the correct command line options for threading: -tWM"
+
+#elif defined  __MWERKS__
+//  Metrowerks CodeWarrior
+#   error "Compiler threading support is not turned on. Please set the correct command line options for threading: either -runtime sm, -runtime smd, -runtime dm, or -runtime dmd"
+
+#elif defined  __SUNPRO_CC
+//  Sun Workshop Compiler C++
+#   error "Compiler threading support is not turned on. Please set the correct command line options for threading: -mt"
+
+#elif defined __HP_aCC
+//  HP aCC
+#   error "Compiler threading support is not turned on. Please set the correct command line options for threading: -mt"
+
+#elif defined(__IBMCPP__)
+//  IBM Visual Age
+#   error "Compiler threading support is not turned on. Please compile the code with the xlC_r compiler"
+
+#elif defined _MSC_VER
+//  Microsoft Visual C++
+//
+//  Must remain the last #elif since some other vendors (Metrowerks, for
+//  example) also #define _MSC_VER
+#  error "Compiler threading support is not turned on. Please set the correct command line options for threading: either /MT /MTd /MD or /MDd"
+
+#else
+
+#  error "Compiler threading support is not turned on.  Please consult your compiler's documentation for the appropriate options to use"
+
+#endif // compilers
+
+#endif // BOOST_HAS_THREADS
+
+#endif // BOOST_CONFIG_REQUIRES_THREADS_HPP