loong64 arch is not supported

[zhangyongding]

github.com/creack/goselect

../../../../pkg/mod/github.com/creack/goselect@v0.1.2/fdset.go:14:14: undefined: NFDBITS
../../../../pkg/mod/github.com/creack/goselect@v0.1.2/fdset.go:19:14: undefined: NFDBITS
../../../../pkg/mod/github.com/creack/goselect@v0.1.2/fdset.go:24:21: undefined: NFDBITS

[cmaglie]

@zhangyongding
Does #149 fix it?