enable ctrl bind config for various programs

Add ctrl_vty_init() calls and feed the ctrl_vty_get_bind_addr() return value to
ctrl_interface_setup() in the following programs:

  osmo-bsc
  osmo-bsc_nat
  osmo-nitb
  osmo-sgsn

For osmo-sgsn, move the control interface setup invocation below the config
parsing, so that the ctrl_vty_get_bind_addr() can return the configured
address.
diff --git a/openbsc/src/gprs/sgsn_ctrl.c b/openbsc/src/gprs/sgsn_ctrl.c
index eff94e0..ccf5076 100644
--- a/openbsc/src/gprs/sgsn_ctrl.c
+++ b/openbsc/src/gprs/sgsn_ctrl.c
@@ -73,7 +73,8 @@
 	return rc;
 }
 
-struct ctrl_handle *sgsn_controlif_setup(struct gsm_network *net, uint16_t port)
+struct ctrl_handle *sgsn_controlif_setup(struct gsm_network *net,
+					 const char *bind_addr, uint16_t port)
 {
-	return ctrl_interface_setup(net, port, NULL);
+	return ctrl_interface_setup_dynip(net, bind_addr, port, NULL);
 }