host: Stop job when one side of attached TTY disconnects
host: Stop job when one side of attached TTY disconnects

This ensures that jobs are cleaned up properly when clients
disconnect without signalling the job to exit separately.

Signed-off-by: Jonathan Rudenberg <3692bfa45759a67d83aedf0045f6cb635a966abf@titanous.com>

lmars/flynn,flynn/flynn,lmars/flynn,lmars/flynn,philiplb/flynn,lmars/flynn,lmars/flynn,philiplb/flynn,flynn/flynn,philiplb/flynn,flynn/flynn,philiplb/flynn,philiplb/flynn,flynn/flynn,flynn/flynn