After paying more attention: things think that libc.so. is in /usr/lib sometimes, e.g. /usr/bin/login: -lutil.7 => /usr/lib/libutil.so.7 -lc.12 => /usr/lib/libc.so.12 -lcrypt.1 => /usr/lib/libcrypt.so.1 -lpam.4 => /usr/lib/libpam.so.4
/usr/lib/libc.so.12 is a symlink to the one in /lib, but that is where the binary thinks it should be.