Simplify dependency checking code for mod_proxy_fdpass. This also fixes

mod_proxy_fdpass being built shared even with --enable-mods-static=reallyall.

Document bug/limitiation in APACHE_MODULE macro.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1154126 13f79535-47bb-0310-9956-ffa450edef68