Compilation/linking error in Mac OSX

[Ant-1]

I use MacPorts for MySQL (5.0.86) and libmemcached (0.32). They're installed in /opt/local.
When I try to configure:
sudo ./configure --with-mysql=/opt/local/bin/mysql_config5 --libdir=/opt/local/lib/mysql5 --with-libmemcached=/opt/local
I get the error:
checking for libmemcached >= 0.17... configure: error: libmemcached not found

So I remove the libmemcached test from configure.ac, run autoconf again, and configure with:
sudo ./configure --with-mysql=/opt/local/bin/mysql_config5 --libdir=/opt/local/lib/mysql5 CFLAGS=-I/opt/local/include LDFLAGS="-L/opt/local/lib -R/opt/local/lib"

'Make' goes well too, from what I can tell.

Then I copy contents of src/.libs to /usr/lib, because MySQL won't see the libs elsewhere.

Then I try to run:
mysql -u root -p mysql < sql/install_functions.sql
And I get the error message:
ERROR 1126 (HY000) at line 38: Can't open shared library 'libmemcached_functions_mysql.so' (errno: 2 dlopen(libmemcached_functions_mysql.so, 2): no suitable image found. Did find:
 /usr/lib/libmemcached_functions_mysql.so: mach-)

So MySQL finds the compiled lib, but can't make it work. Any ideas?