redirector: unmount on TERM and setuid after interrupt
redirector: unmount on TERM and setuid after interrupt

Issue: KBFS-2774

keybase/client,keybase/kbfs,keybase/kbfs,keybase/client,keybase/client,keybase/client,keybase/kbfs,keybase/client,keybase/client,keybase/client,keybase/kbfs,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client