defaults: assign TMSI by default

When using ciphering, the TMSI is an important part of the ciphering. To guard
against users forgetting to set 'assign tmsi' in the config and compromising
their ciphering unknowingly, the default should be to use a TMSI.

To optimize in an unencrypted network, 'no assign tmsi' config can still switch
off TMSI use.

Change-Id: If115e95bebc314bedb50faf3993b52071fee5c1e

src/libvlr/vlr.c

@@ -995,6 +995,9 @@ struct vlr_instance *vlr_alloc(void *ctx, const struct vlr_ops *ops)
 	INIT_LLIST_HEAD(&vlr->operations);
 	memcpy(&vlr->ops, ops, sizeof(vlr->ops));
 
+	/* defaults */
+	vlr->cfg.assign_tmsi = true;
+
 	/* osmo_auth_fsm.c */
 	osmo_fsm_register(&vlr_auth_fsm);
 	/* osmo_lu_fsm.c */