Don't ever attempt to initialise a std::locale with a UTF-8 locale on Windows -*- Mode: Diff -*-

--- libs/locale/src/boost/locale/std/std_backend.cpp
+++ libs/locale/src/boost/locale/std/std_backend.cpp
@@ -138,10 +138,14 @@
                 } else
                     name_ = "C";
             } else {
+#if !defined(BOOST_WINDOWS)
                 if(loadable(lid)) {
                     name_ = lid;
                     utf_mode_ = utf8_support::native;
                 } else {
+#else
+                {
+#endif
                     std::vector<std::string> alt_names;
                     if(l_win)
                         alt_names.push_back(l_win.name);