In my understanding they should be symlinks to /usr/lib64/libau.so.2.2 and not individual files. Additionally this makes trouble when the ld.so.cache is regenerated: >>> Regenerating /etc/ld.so.cache... /sbin/ldconfig: /usr/lib/libau.so.2 is not a symbolic link In every emerge.
This one will be fixed upstream, so will be part of next release.