Add missing b2 testing module import.

examples/Jamfile.v2

@@ -3,6 +3,8 @@
 # subject to 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 ;
+
 run books.cpp ;
 run point.cpp ;
 run portable.cpp ;