Require (linux || freebsd), because the code already does that, in practice.
This just means macOS users of IDEs aren't hit with thousands of compilation
errors (and then the IDE can open an Linux-specific file and then process it
under the Linux assumption, which works much better).
This commit ONLY replaces
//go:build !remote
with
//go:build !remote && (linux || freebsd)
and is split from the rest to allow mechanically verifying that fact,
and focusing a review on the other kinds of changes.
Signed-off-by: Miloslav Trmač <mitr@redhat.com>
