[disk][darwin] fix build with latest x/sys

[tmm1]

fixes build on darwin with golang.org/x/sys v0.0.0-20201007165808-a893ed343c85

# github.com/shirou/gopsutil/disk
../../go/pkg/mod/github.com/fancybits/[email protected]+incompatible/disk/disk_darwin.go:67:51: cannot use stat.Mntfromname[:] (type []byte) as type []int8 in argument to common.IntToString
../../go/pkg/mod/github.com/fancybits/[email protected]+incompatible/disk/disk_darwin.go:68:49: cannot use stat.Mntonname[:] (type []byte) as type []int8 in argument to common.IntToString
../../go/pkg/mod/github.com/fancybits/[email protected]+incompatible/disk/disk_darwin.go:69:50: cannot use stat.Fstypename[:] (type []byte) as type []int8 in argument to common.IntToString
../../go/pkg/mod/github.com/fancybits/[email protected]+incompatible/disk/disk_darwin.go:85:43: cannot use stat.Fstypename[:] (type []byte) as type []int8 in argument to common.IntToString

[audiolion]

Created an issue #958 to track this

[Lomanic]

I confirmed that it now builds with GOOS=darwin go build github.com/shirou/gopsutil/... after updating x/sys. That's the same fix as freebsd in #895 so should be good (didn't test). I think we are probably going to see similar breaking changes from x/sys with openbsd.

Could you update Gopkg.lock with dep? See https://golang.github.io/dep/docs/daily-dep.html#updating-dependencies

[Lomanic]

Superseded by #970.