In r404674 the AST_TEST_DEFINE(test_REPLACE) test was added
that made use of a function that doesn't exist in 1.8. This
fixes that by reverting to directly accessing chan varshead.
Reported by: Tzafrir Cohen
(issue ASTERISK-22910)
git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.8@404951 65c4cc65-6c06-0410-ace0-fbb531ad65f3