debian: don't fail postinst when upgrading chroot

debian: don't fail postinst when upgrading chroot

If we're upgrading a systemd-enabled chroot we'll fail because systemctl
can't connect to a running systemd (nor should it).  We don't need to
issue daemon-reload inside a chroot that doesn't have a running systemd,
so we can ignore the return value.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Nathan Scott <nathans@debian.org>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>