Suppress MSVC level 4 warnings

test/mp_replace_at.cpp

@@ -1,5 +1,5 @@
 
-//  Copyright 2015, 2017 Peter Dimov.
+// Copyright 2015, 2017 Peter Dimov.
 //
 // Distributed under the Boost Software License, Version 1.0.
 //
@@ -7,6 +7,10 @@
 // http://www.boost.org/LICENSE_1_0.txt
 
 
+#if defined(_MSC_VER)
+#pragma warning( disable: 4804 ) // '>=': unsafe use of type 'bool' in operation
+#endif
+
 #include <boost/mp11/algorithm.hpp>
 #include <boost/mp11/list.hpp>
 #include <boost/mp11/integral.hpp>