Add <warnings>extra to test/Jamfile

test/Jamfile.v2

@@ -1,18 +1,21 @@
-# Boost Exception Library test Jamfile
+# Boost ThrowException Library test Jamfile
 #
 # Copyright (c) 2006-2009 Emil Dotchevski and Reverge Studios, Inc.
+# Copyright 2019 Peter Dimov
 #
 # 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)
 
 import testing ;
 
+project : requirements <warnings>extra <warnings-as-errors>on ;
+
 run throw_exception_test.cpp ;
 run throw_exception_no_exceptions_test.cpp ;
 run throw_exception_no_integration_test.cpp ;
 run throw_exception_no_both_test.cpp ;
 
-compile-fail throw_exception_fail.cpp ;
+compile-fail throw_exception_fail.cpp : -<warnings-as-errors>on ;
 
 run throw_exception_test2.cpp ;
 run throw_exception_test3.cpp ;