If UML is not run by a shell it can happen that UML
will kill unrelated proceses upon a fatal exit because
it issues a kill(0, ...).
To prevent such oddities we create a new session in main().
Reported-and-tested-by: NRichard W.M. Jones <rjones@redhat.com>
Signed-off-by: NRichard Weinberger <richard@nod.at>