Build fails on aix/ppc64

[jtroy]

When trying to build on AIX, the following error occurs:

-bash-5.2$ go version
go version go1.23.1 aix/ppc64
-bash-5.2$ go build .
# github.com/IBM/nzgo/v12
./connector.go:102:13: undefined: userCurrent

It looks like a simple matter of adding the aix build tag. I will submit a PR with a suggested fix.