Add a modified form of the patch in PR 7848 to prevent people

from using specially crafted vhost names to write to any .log file on
the system.

PR: 7848
Obtained from:
Submitted by:	Daniel Matuschek <daniel.matuschek@swisscom.com> and Marc Slemko
Reviewed by:


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@89771 13f79535-47bb-0310-9956-ffa450edef68