A follow-up to r22207, fixing Bourne shell portability.
A follow-up to r22207, fixing Bourne shell portability.

* subversion/tests/cmdline/davautocheck.sh
  Use 'unset' instead of 'export -n'.

Suggested by: Peter Samuelson <peter@p12n.org>
Review by: blair

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion