Support new configuration feature

Support new configuration feature

  -DWITH_MODULES=d:/path/to/mod_foo.c,d:/path/to/mod_bar.c,

analogous to --with-module=modpath:/path/to/mod_foo.c,...
with the autoconf-based build.

This introduces a dependency on awk, but only for users that
use this feature.  Other users will get the canned
os/win32/modules.c.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1518414 13f79535-47bb-0310-9956-ffa450edef68