apachectl: Fix a problem finding envvars if sbindir != bindir.

PR:            30723
Submitted by:  Friedrich Haubensak <hsk imb-jena.de>
Reviewed by:   Jeff Trawick


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@104701 13f79535-47bb-0310-9956-ffa450edef68