Fix merging of AddDefaultCharset directive.

PR: 5872
Submitted by:	Jun Kuriyama <kuriyama@imgsrc.co.jp>
Reviewed by:	Jeff Trawick, Jim Jagielski


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@86180 13f79535-47bb-0310-9956-ffa450edef68