configure question re libxml2 on ppc64 el4

I realize this isn't an environment that a lot of folks build on, but
what I've got here is a ppc64 "machine" running EL4 in virtual partition
on an iSeries machine, and I'm working through some build issues on the
configure step.

Currently I've got libxml2 installed in both /usr/lib/ and /usr/lib64,
with 32bit and 64bit version in the appropriate spots. A test configure
fails

The test configure invokation of

CFLAGS="-m64" ./configure linuxppc64gcc --with-libdir=lib64 \
--with-libxml-dir=/usr/lib64

fails in the XML part of the extensions. Specifically, here's the tail
end of the config.log:

---------------
/* The GNU C library defines this for functions which it implements
to always fail with ENOSYS. Some functions are actually named
something starting with __ and the normal name is an alias. */
#if defined (__stub_crypt_r) || defined (__stub___crypt_r)
choke me
#else
crypt_r();
#endif

; return 0; }
configure:19021: checking whether to include gcov symbols
configure:19184: checking whether to include debugging symbols
configure:19226: checking layout of installed files
configure:19261: checking path to configuration file
configure:19295: checking where to scan for configuration files
configure:19331: checking whether to enable safe mode by default
configure:19366: checking for safe mode exec dir
configure:19410: checking whether to enable PHP's own SIGCHLD handler
configure:19448: checking whether to enable magic quotes by default
configure:19486: checking whether to explicitly link against libgcc
configure:19566: checking whether to enable short tags by default
configure:19604: checking whether to enable dmalloc
configure:19692: checking whether to enable IPv6 support
configure:19722: checking how big to make fd sets
configure:19793: checking whether to enable LIBXML support
configure:19841: checking libxml2 install dir
configure:19870: checking for xml2-config path
configure:20028: checking whether libxml build works
configure:20055: gcc -o conftest -m64 -L/usr/lib64 conftest.c

-lresolv -lm -ldl -lnsl -lxml2 -lz -lm 1>&5
/usr/bin/ld: skipping incompatible /usr/lib/gcc/ppc64-redhat-linux/3.4.6/../../../libxml2.so when searching for -lxml2
/usr/bin/ld: skipping incompatible /usr/lib/gcc/ppc64-redhat-linux/3.4.6/../../../libxml2.a when searching for -lxml2
/usr/bin/ld: skipping incompatible /usr/lib/libxml2.so when searching for -lxml2
/usr/bin/ld: skipping incompatible /usr/lib/libxml2.a when searching for -lxml2
/usr/bin/ld: cannot find -lxml2
collect2: ld returned 1 exit status
configure: failed program was:
#line 20044 "configure"
#include "confdefs.h"


char xmlInitParser();
int main() {
xmlInitParser();
return 0;
}

---------------

I think what I need to know is how to convince configure tell ld where
to properly look for libxml2.so and libxml2.a in /usr/lib64 instead of
/usr/lib. Any suggestions how to do that, or better questions to aks?


--
12. One of my advisors will be an average five-year-old child. Any flaws in my
plan that he is able to spot will be corrected before implementation.
--Peter Anspach's list of things to do as an Evil Overlord