Update boost to 1.71 and add asio

boost/predef/platform/windows_uwp.h

@@ -0,0 +1,60 @@
+/*
+Copyright James E. King III, 2017
+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)
+*/
+
+#ifndef BOOST_PREDEF_PLAT_WINDOWS_UWP_H
+#define BOOST_PREDEF_PLAT_WINDOWS_UWP_H
+
+#include <boost/predef/make.h>
+#include <boost/predef/os/windows.h>
+#include <boost/predef/version_number.h>
+
+/*`
+[heading `BOOST_PLAT_WINDOWS_UWP`]
+
+[@http://docs.microsoft.com/windows/uwp/ Universal Windows Platform]
+is available if the current development environment is capable of targeting 
+UWP development.
+
+[table
+    [[__predef_symbol__] [__predef_version__]]
+
+    [[`__MINGW64_VERSION_MAJOR` from `_mingw.h`] [`>= 3`]]
+    [[`VER_PRODUCTBUILD` from `ntverp.h`] [`>= 9200`]]
+]
+*/
+
+#define BOOST_PLAT_WINDOWS_UWP BOOST_VERSION_NUMBER_NOT_AVAILABLE
+#define BOOST_PLAT_WINDOWS_SDK_VERSION BOOST_VERSION_NUMBER_NOT_AVAILABLE
+
+#if BOOST_OS_WINDOWS
+//  MinGW (32-bit) has no ntverp.h header
+#if !defined(__MINGW32__)
+#   include <ntverp.h>
+#   undef BOOST_PLAT_WINDOWS_SDK_VERSION
+#   define BOOST_PLAT_WINDOWS_SDK_VERSION BOOST_VERSION_NUMBER(0, 0, VER_PRODUCTBUILD)
+#endif
+
+// 9200 is Windows SDK 8.0 from ntverp.h which introduced family support
+#if ((BOOST_PLAT_WINDOWS_SDK_VERSION >= BOOST_VERSION_NUMBER(0, 0, 9200)) || \
+     (defined(__MINGW64__) && __MINGW64_VERSION_MAJOR >= 3))
+#   undef BOOST_PLAT_WINDOWS_UWP
+#   define BOOST_PLAT_WINDOWS_UWP BOOST_VERSION_NUMBER_AVAILABLE
+#endif
+#endif
+
+#if BOOST_PLAT_WINDOWS_UWP
+#   define BOOST_PLAT_WINDOWS_UWP_AVAILABLE
+#   include <boost/predef/detail/platform_detected.h>
+#   include <winapifamily.h>    // Windows SDK
+#endif
+
+#define BOOST_PLAT_WINDOWS_UWP_NAME "Universal Windows Platform"
+
+#endif
+
+#include <boost/predef/detail/test.h>
+BOOST_PREDEF_DECLARE_TEST(BOOST_PLAT_WINDOWS_UWP, BOOST_PLAT_WINDOWS_UWP_NAME)