selftest: Use new fake_acls module

selftest: Use new fake_acls module

This isolates us from the OS ACL library, and allows chown to 'work'
when we are non-root.  In turn, this ensures that we can test the SMB
-> POSIX layer even when the OS would refuse the set due to non-root
or simply not having acls enabled on this particular file system.

This should make a number of build farm tests much more reliable, and
allows a number more tests to pass.

Andrew Bartlett