In auth-pam plugin clear the password after use

In auth-pam plugin clear the password after use

v2: Change the plugin open to use v3 API so that secure_memzero()
    exported from OpenVPN can be used.
v3: Relaxe API compatibility check: struct version 4 or higher
    will have secure_memzero exported.

Note: context is cast as (openvpn_plugin_handle_t *) for consistency
with the current plugin header. If/when the header is fixed, change
this cast as well.

Signed-off-by: Selva Nair <selva.nair@gmail.com>
Acked-by: David Sommerseth <davids@openvpn.net>
Message-Id: <1494359069-13824-1-git-send-email-selva.nair@gmail.com>
URL: http://www.mail-archive.com/search?l=mid&q=1494359069-13824-1-git-send-email-selva.nair@gmail.com
Signed-off-by: David Sommerseth <davids@openvpn.net>