Fix `require ...' directive parsing in mod_auth, mod_auth_dbm and mod_auth_db

by using ap_getword_white() (which uses ap_isspace()) instead of
ap_getword(..., ' ') (which parses only according to spaces but not tabs).

Submitted by: James Morris <jmorris@intercode.com.au>
Reviewed and extended to other mods: Ralf S. Engelschall
PR: 3105


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@82209 13f79535-47bb-0310-9956-ffa450edef68