unbound: Only launch one process

unbound: Only launch one process

When unbound is running multiple threads, we have observed
that queries where sent for each thread.

Since no user should have so much DNS traffic that more than
one processor core is being saturated, this is a safe change.

Signed-off-by: Peter Müller <peter.mueller@ipfire.org>
Signed-off-by: Arne Fitzenreiter <arne.fitzenreiter@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
Signed-off-by: Arne Fitzenreiter <arne_f@ipfire.org>