Fix detection of SCGI and suEXEC when mod_ruid2 is installed

This implements some logic to not provide an error about SCGI or suEXEC when mod_ruid2 is installed, since mod_ruid2 provides functionality that suEXEC does. Also, on cPanel systems, when mod_ruid2 is installed, we do not run suEXEC regardless of whether or not it's installed.