Revert "session MAINTENANCE remove unused functions"

This reverts commit 3a13405867b0407483aa2f54e9137cca6de08378.
diff --git a/src/session.c b/src/session.c
index b2227f9..feeca8f 100644
--- a/src/session.c
+++ b/src/session.c
@@ -1375,6 +1375,26 @@
     return type;
 }
 
+#ifdef NC_ENABLED_SSH
+
+static void
+nc_ssh_init(void)
+{
+    ssh_threads_set_callbacks(ssh_threads_get_pthread());
+    ssh_init();
+}
+
+static void
+nc_ssh_destroy(void)
+{
+    FIPS_mode_set(0);
+    CONF_modules_unload(1);
+    nc_thread_destroy();
+    ssh_finalize();
+}
+
+#endif /* NC_ENABLED_SSH */
+
 #ifdef NC_ENABLED_TLS
 
 #if OPENSSL_VERSION_NUMBER < 0x10100000L // < 1.1.0