Added RHAPSODY (Mac OS X Server) support. MAP_TMPFILE defined

as an alternate mechanism for mmap'd shared memory for RHAPSODY.
ap_private_extern defined to hide symbols that conflict with loaded
dynamic libraries on the NEXT and RHAPSODY platforms.

Submitted code was modified by Roy to use ap_private_extern instead of
directly using __private_extern__, and MAP_TMPFILE instead of TMP_MAP_ANON,
as suggested by Dean.

Submitted by:	Wilfredo Sanchez <wsanchez@apple.com>
Reviewed by:	Roy Fielding, Dean Gaudet


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@82049 13f79535-47bb-0310-9956-ffa450edef68