management: preserve wait_for_push field when asking for user/pass

management: preserve wait_for_push field when asking for user/pass

With the introduction of the wait_for_push field in the auth_user_pass
structure, we have to make sure that such field is not accidentally
erased when the management asks the user for user/pass.

Erasing such field would mess up the logic introduced by
("Ignore auth-nocache for auth-user-pass if auth-token is pushed").

Thanks to David Sommerseth for the preliminary analysis and debugging.

Reported-by: Steven Haigh <netwiz@crc.id.au>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
Tested-by: Steven Haigh <netwiz@crc.id.au>
Acked-by: David Sommerseth <davids@openvpn.net>
Message-Id: <20170707140108.31612-1-a@unstable.cc>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg15015.html
Signed-off-by: David Sommerseth <davids@openvpn.net>
(cherry picked from commit 3322c558fa742cb823fa919f682486973abc4f8e)