We should use pam property - this works on both LinuxPAM and OpenPAM

diff -ur openvpn-2.0.7.orig/plugin/auth-pam/Makefile openvpn-2.0.7/plugin/auth-pam/Makefile
--- openvpn-2.0.7.orig/plugin/auth-pam/Makefile	2005-11-02 18:02:49 +0000
+++ openvpn-2.0.7/plugin/auth-pam/Makefile	2006-10-11 12:05:55 +0100
@@ -4,7 +4,7 @@
 
 # If PAM modules are not linked against libpam.so, set DLOPEN_PAM to 1. This
 # must be done on SUSE 9.1, at least.
-DLOPEN_PAM=1
+DLOPEN_PAM=0
 
 ifeq ($(DLOPEN_PAM),1)
 	LIBPAM=-ldl
diff -ur openvpn-2.0.7.orig/plugin/auth-pam/pamdl.c openvpn-2.0.7/plugin/auth-pam/pamdl.c
--- openvpn-2.0.7.orig/plugin/auth-pam/pamdl.c	2005-11-02 18:02:49 +0000
+++ openvpn-2.0.7/plugin/auth-pam/pamdl.c	2006-10-11 12:04:48 +0100
@@ -10,7 +10,6 @@
 #include <stdio.h>
 #include <dlfcn.h>
 #include <security/pam_appl.h>
-#include <security/_pam_macros.h>
 
 #include "pamdl.h"
 
@@ -74,7 +73,7 @@
     return real_pam_set_item(pamh, item_type, item);
 }
 
-int pam_get_item(const pam_handle_t *pamh, int item_type, const void **item)
+int pam_get_item(pam_handle_t *pamh, int item_type, const void **item)
 {
     int (*real_pam_get_item)(const pam_handle_t *, int, const void **);
     RESOLVE_PAM_FUNCTION(pam_get_item, int,