- allows empty $val from httpd-2.0/build/config_vars.mk

- allows empty $val from httpd-2.0/build/config_vars.mk
- make code more perlish.
- read and parse the config file only once
- use a hash instead of array for the list of internal config vars to
  test against
- added -h option (just print usage)
- wrapped numerous print STDERR calls into a simpler error() and
  notice() subs
- simplified some of the logic in if's using perl constructs.

Submitted by:	Stas Bekman <stas@stason.org>

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@90732 13f79535-47bb-0310-9956-ffa450edef68