linking with multiarch libs does not work

On 11.10:

 linux-vdso.so.1 => (0x00007fff3f7ff000)
 libmysqlclient_r.so.16 => /usr/lib/libmysqlclient_r.so.16 (0x00007f3ce5476000)
 libnsmysql.so => not found
 libnsd.so => not found
 libnsthread.so => not found
 libtcl8.4.so.0 => not found
 libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f3ce5270000)
 libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f3ce5053000)
 libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f3ce4dcf000)
 libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f3ce4bb8000)
 libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f3ce4819000)
 libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f3ce4601000)
 /lib64/ld-linux-x86-64.so.2 (0x00007f3ce5aa5000)

On precise:

 linux-vdso.so.1 => (0x00007fffbddff000)
 libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007ffceafcd000)
 /lib64/ld-linux-x86-64.so.2 (0x00007ffceb596000)