turns out STDOUT may have been redirected, in which case tcgetpgrp will
authorespie <espie@openbsd.org>
Sun, 31 Jan 2021 15:22:55 +0000 (15:22 +0000)
committerespie <espie@openbsd.org>
Sun, 31 Jan 2021 15:22:55 +0000 (15:22 +0000)
commit7d028f8057c14609007b0bb995bd96865afd6322
treec11f6dd89cbfad4c729bbe5a8cd7c470b8ac563c
parente741336dd40440abd7ca9c6a74c04e1e2969770e
turns out STDOUT may have been redirected, in which case tcgetpgrp will
return -1, in which case we never need to suppress output.

noticed by Mark Patruck
usr.sbin/pkg_add/OpenBSD/State.pm