versioning question (specifying version to link to)

[Lynn Winebarger <owinebar at free-expression dot org>]

  This may be directed at the wrong list.
   Anyway, I'm having a problem with getting the wrong version of a library 
linked in.  The situation is this:  I compiled a version of libexpat (xml 
parser library) from a autoconf-ized version I found on the internet (when
the main distribution was still un-autoconf'ed).  For some reason, the
people who did the conversion set the version to 3.1.0 (the release was
1.2 I think).
   Now comes along a change in maintainers of libexpat, and the main
distribution is now autoconfed at release 1.95.  But they put the library 
version at 0.0.1.  The question is, how do I get the newer (in reality) 
version linked to when ld (or libtool, not sure exactly which makes
the decision) seems to prefer the older version.  (I'm trying to compile
a version of php).  Unfortunately, this is on a production server, so I
can't just remove the old libraries.  Of course, I could up the version on
the newer one as a temporary measure, and then recompile the whole 
thing on a separate build host (which is probably what I'll do).
    But I'm curious as to how I could change this behaviour anyway.
The system is redhat 6.2 linux, plus updates.  A kink is that the newer 
version is in a weird location I'm using for chroot purposes.  The weird
location is in ld.so.conf and ldconfig finds it.  But I'm pretty sure it's 
including the latest version of the include file (because there's no
versioning checking on the includes and I specified the weird location
via environment variable to the configure script).

Any help would be appreciated.  The libtool manual goes over how to specify
the version of a library you create pretty thoroughly, but doesn't talk much 
about versions to link to (unless I missed something).

Thanks,
Lynn