mod_isapi: Ensure we walk through all the methods the developer may have

  employed to report their HTTP status result code.

PR: 16637, 30033
Submitted by: Matt Lewandowsky <matt iamcode.net>
Reviewed by: William Rowe

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@416272 13f79535-47bb-0310-9956-ffa450edef68