Set a reasonable fallback for get_rundir

If get_rundir can't find XDG_RUNTIME_DIR in the environment, it'll
attempt to build a path using ~/.cache/lxc/run/. Should that fail
because of missing $HOME in the environment, it'll then return NULL an
all callers will fail in that case.

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
rundir: Fix the uid == 0 case

This makes get_rundir actually do what I meant it to do... for some
reason I missed that one in testing...

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
network: set mtu of unpriv veth to the bridge's mtu

That's to make sure that if the bridge has a higher than 1500
mtu, the new veth (defaulting to 1500) doesn't lower it.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>
rundir: Fix memory leaks

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>