Builds broken on macOS with Go 1.18

[mjlshen]

❯ make build
go get
go mod verify
all modules verified
go mod vendor
go build -mod=vendor -o pd ./command
# golang.org/x/sys/unix
vendor/golang.org/x/sys/unix/zsyscall_darwin_amd64.go:28:3: //go:linkname must refer to declared function or variable
vendor/golang.org/x/sys/unix/zsyscall_darwin_amd64.go:43:3: //go:linkname must refer to declared function or variable
vendor/golang.org/x/sys/unix/zsyscall_darwin_amd64.go:59:3: //go:linkname must refer to declared function or variable
vendor/golang.org/x/sys/unix/zsyscall_darwin_amd64.go:75:3: //go:linkname must refer to declared function or variable
vendor/golang.org/x/sys/unix/zsyscall_darwin_amd64.go:90:3: //go:linkname must refer to declared function or variable
vendor/golang.org/x/sys/unix/zsyscall_darwin_amd64.go:105:3: //go:linkname must refer to declared function or variable
vendor/golang.org/x/sys/unix/zsyscall_darwin_amd64.go:121:3: //go:linkname must refer to declared function or variable
vendor/golang.org/x/sys/unix/zsyscall_darwin_amd64.go:136:3: //go:linkname must refer to declared function or variable
vendor/golang.org/x/sys/unix/zsyscall_darwin_amd64.go:151:3: //go:linkname must refer to declared function or variable
vendor/golang.org/x/sys/unix/zsyscall_darwin_amd64.go:166:3: //go:linkname must refer to declared function or variable
vendor/golang.org/x/sys/unix/zsyscall_darwin_amd64.go:166:3: too many errors
make: *** [build] Error 2

According to golang/go#49219, this can be solved by updating the golang.org/x/sys/unix package, happy to make a PR for this.