SMPP: make smpp_smsc_stop() static

It's only used in a single file so there's no point exposing it via header.

Related: OS#5568
Change-Id: I3d0d850ffe6ebf9d623c1f250d4293a3c427d5d8
diff --git a/include/osmocom/smpp/smpp_smsc.h b/include/osmocom/smpp/smpp_smsc.h
index 9607079..6d76475 100644
--- a/include/osmocom/smpp/smpp_smsc.h
+++ b/include/osmocom/smpp/smpp_smsc.h
@@ -107,7 +107,6 @@
 int smpp_smsc_conf(struct smsc *smsc, const char *bind_addr, uint16_t port);
 int smpp_smsc_start(struct smsc *smsc, const char *bind_addr, uint16_t port);
 int smpp_smsc_restart(struct smsc *smsc, const char *bind_addr, uint16_t port);
-void smpp_smsc_stop(struct smsc *smsc);
 
 void smpp_esme_get(struct smpp_esme *esme);
 void smpp_esme_put(struct smpp_esme *esme);
diff --git a/src/libsmpputil/smpp_smsc.c b/src/libsmpputil/smpp_smsc.c
index 0ee5b62..d54b3c1 100644
--- a/src/libsmpputil/smpp_smsc.c
+++ b/src/libsmpputil/smpp_smsc.c
@@ -966,6 +966,16 @@
 	return 0;
 }
 
+/*! /brief Close SMPP connection. */
+static void smpp_smsc_stop(struct smsc *smsc)
+{
+	if (smsc->listen_ofd.fd > 0) {
+		close(smsc->listen_ofd.fd);
+		smsc->listen_ofd.fd = 0;
+		osmo_fd_unregister(&smsc->listen_ofd);
+	}
+}
+
 /*! \brief Bind to given address and port and accept connections.
  * \param[in] bind_addr Local IP address, may be NULL for any.
  * \param[in] port TCP port number, may be 0 for default SMPP (2775).
@@ -1004,13 +1014,3 @@
 		return smpp_smsc_start(smsc, smsc->bind_addr, smsc->listen_port);
 	return 0;
 }
-
-/*! /brief Close SMPP connection. */
-void smpp_smsc_stop(struct smsc *smsc)
-{
-	if (smsc->listen_ofd.fd > 0) {
-		close(smsc->listen_ofd.fd);
-		smsc->listen_ofd.fd = 0;
-		osmo_fd_unregister(&smsc->listen_ofd);
-	}
-}