applied the same fix as r1709 and r1710.  This will make it possible to run tests in a separate build tree.  (trac ticket #143)

also applied the DRY principle to unittest_util*: remove the local copies and simply referred to the dns/tests versions of these files.


git-svn-id: svn://bind10.isc.org/svn/bind10/trunk@1713 e5f2f494-b856-4b98-b285-d166d9295462