Replaced use of WIN32 define with HAVE_DRIVE_LETTERS to indicate

when the OS allows a DOS drive letter within pathnames.

Submitted by:	Brian Havard <brianh@kheldar.apana.org.au>
Reviewed by:	Roy Fielding


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@82866 13f79535-47bb-0310-9956-ffa450edef68