Fix crash of RC4 encrypted password notice.

[racke]

As reported by Jacques Tissot on the mailing list:

DIED: [Tue Jul 23 08:47:54 2019] wwsympa.fcgi: Error on incoming parameter "$data", it must be a ref on HASH or a ref on ARRAY at /home/sympa/bin/Sympa.pm line 422.
at /usr/share/perl5/CGI/Carp.pm line 362.
                CGI::Carp::realdie('[Tue Jul 23 08:47:54 2019] wwsympa.fcgi: Error on incoming pa...') called at /usr/share/perl5/CGI/Carp.pm line 461
                CGI::Carp::die('Error on incoming parameter "$data", it must be a ref on HASH...') called at /home/sympa/bin/Sympa.pm line 422
                Sympa::send_notify_to_listmaster('*', 'password_encrypted') called at /home/sympa/bin/Sympa/WWW/Auth.pm line 160
                Sympa::WWW::Auth::authentication('unifr.ch', '<loginName>', '<password>') called at /home/sympa/bin/Sympa/WWW/Auth.pm line 60
                Sympa::WWW::Auth::check_auth('unifr.ch', '<loginName>', '<password>') called at /home/sympa/bin/wwsympa.fcgi line 3155
                main::do_login() called at /home/sympa/bin/wwsympa.fcgi line 1544

Sympa version: 6.2.44

[ikedas]

This may fix #707.