revert r1026746:

    If an unknown Content-* header is received for a PUT request, we must not
    ignore it but reply with 501 per RFC 2616 9.6.
    
    PR: 42978

Vetoed by Roy T. Fielding:
http://mail-archives.apache.org/mod_mbox/httpd-dev/201102.mbox/%3C9A5A8B62-ED16-4BD3-97DA-8475026BB81D@gbiv.com%3E


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1070061 13f79535-47bb-0310-9956-ffa450edef68