Move settings of user script into set_user_script function

This also fixes commit 567bfc06d051b60e9cdca1f5bb468631b899682a if not all
script options are available by setting options->user_script_used
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1369945603-17169-1-git-send-email-arne@rfc2549.org>
URL: http://article.gmane.org/gmane.network.openvpn.devel/7634

Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit 9b6a5028111cd915b0342fbd2ecd0b9dfd4aa94a)
Move checking of script file access into set_user_script

At the moment script are only checked if P2MP_SERVER is defined. For
CLIENT_ONLY openvpn script were never checked.
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <1369947737-26081-1-git-send-email-arne@rfc2549.org>
URL: http://article.gmane.org/gmane.network.openvpn.devel/7635

Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit e55681a9d802bf1639115d325c1685e5962865d0)