down-root: Improve error messages

down-root: Improve error messages

If down-root fails it will now use warn() to provide some more information
about what went wrong, by retrieving the error message via errno.

Signed-off-by: David Sommerseth <davids@redhat.com>
Acked-by: Steffan Karger <steffan.karger@fox-it.com>
Message-Id: <1416262460-9158-1-git-send-email-openvpn.list@topphemmelig.net>
URL: http://article.gmane.org/gmane.network.openvpn.devel/9247
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit b0f2c521303b7bceb6806680363bc4b9d225e5b8)