Update golang.org/x/sys to work with go1.18

[picatz]

This PR is a follow up to #360, to fix https://github.com/hashicorp/go-getter/runs/6498424476?check_suite_focus=true

...
   ⨯ release failed after 231.07s error=failed to build for darwin_amd64_v1: exit status 2: go: downloading github.com/cheggaaa/pb v1.0.27
...
golang.org/x/sys/unix
Error: /home/runner/go/pkg/mod/golang.org/x/sys@v0.0.0-20190624142023-c5567b49c5d0/unix/zsyscall_darwin_amd64.go:28:3: //go:linkname must refer to declared function or variable
Error: /home/runner/go/pkg/mod/golang.org/x/sys@v0.0.0-20190624142023-c5567b49c5d0/unix/zsyscall_darwin_amd64.go:43:3: //go:linkname must refer to declared function or variable
Error: /home/runner/go/pkg/mod/golang.org/x/sys@v0.0.0-20190624142023-c5567b49c5d0/unix/zsyscall_darwin_amd64.go:59:3: //go:linkname must refer to declared function or variable
Error: /home/runner/go/pkg/mod/golang.org/x/sys@v0.0.0-20190624142023-c5567b49c5d0/unix/zsyscall_darwin_amd64.go:75:3: //go:linkname must refer to declared function or variable
Error: /home/runner/go/pkg/mod/golang.org/x/sys@v0.0.0-20190624142023-c5567b49c5d0/unix/zsyscall_darwin_amd64.go:90:3: //go:linkname must refer to declared function or variable
Error: /home/runner/go/pkg/mod/golang.org/x/sys@v0.0.0-20190624142023-c5567b49c5d0/unix/zsyscall_darwin_amd64.go:105:3: //go:linkname must refer to declared function or variable
Error: /home/runner/go/pkg/mod/golang.org/x/sys@v0.0.0-20190624142023-c5567b49c5d0/unix/zsyscall_darwin_amd64.go:121:3: //go:linkname must refer to declared function or variable
Error: /home/runner/go/pkg/mod/golang.org/x/sys@v0.0.0-20190624142023-c5567b49c5d0/unix/zsyscall_darwin_amd64.go:136:3: //go:linkname must refer to declared function or variable
Error: /home/runner/go/pkg/mod/golang.org/x/sys@v0.0.0-201[90](https://github.com/hashicorp/go-getter/runs/6498424476?check_suite_focus=true#step:8:91)624142023-c5567b49c5d0/unix/zsyscall_darwin_amd64.go:151:3: //go:linkname must refer to declared function or variable
Error: /home/runner/go/pkg/mod/golang.org/x/sys@v0.0.0-20190624142023-c5567b49c5d0/unix/zsyscall_darwin_amd64.go:166:3: //go:linkname must refer to declared function or variable
Error: /home/runner/go/pkg/mod/golang.org/x/sys@v0.0.0-20190624142023-c5567b49c5d0/unix/zsyscall_darwin_amd64.go:166:3: too many errors

For more context, golang.org/x/sys/unix is an indirect dependency from github.com/cheggaaa/pb:

$ go mod why -m golang.org/x/sys
# golang.org/x/sys
github.com/hashicorp/go-getter/cmd/go-getter
github.com/cheggaaa/pb
golang.org/x/sys/unix