get_mapped_rootid: avoid using (uid_t) -1

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
get_mapped_rootid: fix description

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
tests: Update lxc-test-unpriv

Update lxc-test-unpriv to be a bit simpler and more reliable.

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
tests: Fix cleanup in lxc-test-unpriv

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>
tests: Rework lxc-test-usernic

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