unix.CLOCK_MONOTONIC is undefined on NetBSD

[satoqz]

#435 broke NetBSD builds by assuming unix.CLOCK_MONOTONIC to be defined across all unix plaforms.

github.com/coreos/go-systemd/v22/daemon
# github.com/coreos/go-systemd/v22/daemon
../../.go/pkg/mod/github.com/coreos/go-systemd/v22@v22.7.0/daemon/sdnotify_unix.go:31:35: undefined: unix.CLOCK_MONOTONIC

[satoqz]

@Luap99 this is not a duplicate but a separate issue. The same commit in OpenBao builds just fine on FreeBSD, but it fails on NetBSD. We are also on the latest golang.org/x/sys.

[Luap99]

Ah sorry I see it is CLOCK_MONOTONIC missing not the whole function