Uses too-old expat on QNX 6.3.2

Howdy,

When I try to compile Subversion 1.3.1 on QNX 6.3.2, neon's configure
fails because it cannot find expat or libxml. apr-util's configure is
able to detect the system version of expat, but it is too old to be
used by neon. If I remove /usr from the directories that apr-util
searches for expat, it uses its copy of expat, as does neon.

I don't think this is the same problem as issue 699, so I was planning
to file a new issue about it. OK?

-- 
Matt