Originally Posted by camerabambai
ln -s /usr/lib64/libnfsidmap* /usr/lib/
That looks like a hack to fix a bug in a broken SlackBuild, it would be better to fix the SlackBuild so that it installs things properly.
The site you linked is currently down so I can't see what it has on there but getting nfs4 working on Slackware requires a bit less then what has been previously stated in this thread.
First the dependencies that are required libevent, libnfsidmap and libtirpc. (Kerberos is not required unless you need it for authentication.)
Portmap is dead and gone replaced by rpcbind, this also gives us ipv6 support for RPC services.
Then nfs-utils is rebuilt enabling nfs4 (I also suggest upgrading it as well)