enabling option pam for security/openssh on NetBSD

[Emmanuel Dreyfus <Emmanuel.Dreyfus%espci.fr@localhost>]

Hello

security/openssh has pam option that is currently only allowed on Linux.
A comment in options.mk says it causes uninvestigated memory faults.

I gave it a try on NetBSD and it seems to work fine, provided one does
not mix base system OpenSSL and pkgsrc OpenSSL in the various parts
that link together in OpenSSH: for instance, sshd links to libcrypto,
and libpam can load pam_ldap, which links to libldap and libcrypto
again.

But the same principle applies to many other packages. If nobody objects, 
I will make the pam option available on NetBSD.

-- 
Emmanuel Dreyfus
ESPCI ParisTech - Service informatique
Emmanuel.Dreyfus%espci.fr@localhost