Fix compilation with --with-bsd-auth.

Commit 8d3b9cce81 added extra arguments to the sendAuthRequest function,
but neglected this caller inside #ifdef USE_BSD_AUTH.

Per report from Pierre-Emmanuel André.

Discussion: https://www.postgresql.org/message-id/20170519090336.whzmjzrsap6ktbgg@digipea.digitick.local

src/backend/libpq/auth.c

@@ -2262,7 +2262,7 @@ CheckBSDAuth(Port *port, char *user)
 	int			retval;
 
 	/* Send regular password request to client, and get the response */
-	sendAuthRequest(port, AUTH_REQ_PASSWORD);
+	sendAuthRequest(port, AUTH_REQ_PASSWORD, NULL, 0);
 
 	passwd = recv_password_packet(port);
 	if (passwd == NULL)