Add a note about building on AIX with the known compiler bug.

Submitted by:	Shane Owenby <shaneo@raleigh.ibm.com>
Reviewed by:	Ken Coar


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/1.3.x@82287 13f79535-47bb-0310-9956-ffa450edef68