add include <thread>

include/nana/std_thread.hpp

@@ -5,6 +5,7 @@
 #if defined(STD_THREAD_NOT_SUPPORTED)
 
 #if defined(NANA_ENABLE_MINGW_STD_THREADS_WITH_MEGANZ)
+
 #include <mingw.thread.h>
 #else
 #include <boost/thread.hpp>
@@ -13,5 +14,11 @@ namespace std
     typedef boost::thread thread;
 }
 #endif  // (NANA_ENABLE_MINGW_STD_THREADS_WITH_MEGANZ)
+
+#else
+
+#include <thread>
+
 #endif // (STD_THREAD_NOT_SUPPORTED)
+
 #endif // NANA_STD_THREAD_HPP