xauth: add a configuration string option to be passed to XAuth instances

The configuration string is appended to the XAuth backend name, separated by
a colon. The configuration string is passed untouched to the backend, where
it can change the behavior of the XAuth module.

src/libcharon/plugins/xauth_pam/xauth_pam.c

@@ -195,7 +195,7 @@ METHOD(xauth_method_t, destroy, void,
  * Described in header.
  */
 xauth_pam_t *xauth_pam_create_server(identification_t *server,
-									 identification_t *peer)
+									 identification_t *peer, char *profile)
 {
 	private_xauth_pam_t *this;
 

src/libcharon/plugins/xauth_pam/xauth_pam.h

@@ -41,9 +41,10 @@ struct xauth_pam_t {
  *
  * @param server	ID of the XAuth server
  * @param peer		ID of the XAuth client
+ * @param profile	configuration string
  * @return			xauth_pam_t object
  */
 xauth_pam_t *xauth_pam_create_server(identification_t *server,
-									 identification_t *peer);
+									 identification_t *peer, char *profile);
 
 #endif /** XAUTH_PAM_H_ @}*/