Small tweak to clarify a constant.

* tools/hook-scripts/mailer/mailer.py:
  (Config): rename _predefined to PREDEFINED
  (Config.__init__): follow the rename


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1917633 13f79535-47bb-0310-9956-ffa450edef68
1 file changed