'Header Unset' really unsets all values for the field, not
	just the first.

Submitted by:	Robin Langford <rlangfor@US.IBM.Com>
Reviewed by:	Ken Coar


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@83364 13f79535-47bb-0310-9956-ffa450edef68