Properly substitute sbindir as httpd's location in apachectl.

We install $(PROGRAMS) into $(sbindir) not $(bindir), so this is correct.

PR: 7840
Submitted by:	Andreas Hasenack <andreas@netbank.com.br>
Reviewed by:	Justin Erenkrantz


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@94653 13f79535-47bb-0310-9956-ffa450edef68