update boost on linux

linx64/include/boost/asio/detail/impl/win_thread.ipp

@@ -2,7 +2,7 @@
 // detail/impl/win_thread.ipp
 // ~~~~~~~~~~~~~~~~~~~~~~~~~~
 //
-// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+// Copyright (c) 2003-2019 Christopher M. Kohlhoff (chris at kohlhoff dot com)
 //
 // 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)
@@ -56,6 +56,13 @@ void win_thread::join()
   }
 }
 
+std::size_t win_thread::hardware_concurrency()
+{
+  SYSTEM_INFO system_info;
+  ::GetSystemInfo(&system_info);
+  return system_info.dwNumberOfProcessors;
+}
+
 void win_thread::start_thread(func_base* arg, unsigned int stack_size)
 {
   ::HANDLE entry_event = 0;