Make the install-bindist.sh script standalone. (don't require src/helpers)

This could allow us to do binary distributions without source if we choose
to.

PERL detection now makes sure it is perl5 since the 2 scripts in question
(dbmmanage and apxs) require perl5.

Fix some breakage I introduced when creating apachectl.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@83155 13f79535-47bb-0310-9956-ffa450edef68