Remove header files that are already included by other headers.

This avoids problems on some OSes that can't handle the same header
being included twice.

Reviewed by:	Brian Behlendorf, Dean Gaudet
Submitted by:
Obtained from:


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@78804 13f79535-47bb-0310-9956-ffa450edef68