Change uses of std::sprintf in tests to boost::core::snprintf, to avoid deprecation warnings

test/system_category_test.cpp

@@ -8,11 +8,9 @@
 
 // See library home page at http://www.boost.org/libs/system
 
-// Avoid spurious VC++ warnings
-# define _CRT_SECURE_NO_WARNINGS
-
 #include <boost/system/error_code.hpp>
 #include <boost/core/lightweight_test.hpp>
+#include <boost/core/snprintf.hpp>
 #include <cstring>
 #include <cstdio>
 
@@ -65,7 +63,7 @@ std::string sys_strerror( int ev )
     {
         char buffer[ 38 ];
 
-        std::sprintf( buffer, "Unknown error (%d)", ev );
+        boost::core::snprintf( buffer, sizeof( buffer ), "Unknown error (%d)", ev );
         return buffer;
     }