build CHANGE rename too generic macros to libnetconf specific

ENABLE_TLS and ENABLE_SSH are too generic to be used as symbols
exported via header files to the user applications. Therefore the
symbols were renamed to NC_ENABLED_SSH and NC_ENABLED_TLS.
diff --git a/src/session_server.h b/src/session_server.h
index 11baf34..1d919c0 100644
--- a/src/session_server.h
+++ b/src/session_server.h
@@ -201,7 +201,7 @@
  */
 void nc_ps_clear(struct nc_pollsession *ps);
 
-#if defined(ENABLE_SSH) || defined(ENABLE_TLS)
+#if defined(NC_ENABLED_SSH) || defined(NC_ENABLED_TLS)
 
 /**
  * @brief Accept new sessions on all the listening endpoints.
@@ -213,9 +213,9 @@
  */
 int nc_accept(int timeout, struct nc_session **session);
 
-#endif /* ENABLE_SSH || ENABLE_TLS */
+#endif /* NC_ENABLED_SSH || NC_ENABLED_TLS */
 
-#ifdef ENABLE_SSH
+#ifdef NC_ENABLED_SSH
 
 /**
  * @brief Accept a new NETCONF session on an SSH session of a running NETCONF session
@@ -336,9 +336,9 @@
  */
 int nc_server_ssh_endpt_del_authkey(const char *endpt_name, const char *pubkey_path, const char *username);
 
-#endif /* ENABLE_SSH */
+#endif /* NC_ENABLED_SSH */
 
-#ifdef ENABLE_TLS
+#ifdef NC_ENABLED_TLS
 
 /**
  * @brief Add a new TLS endpoint and start listening on it.
@@ -511,6 +511,6 @@
  */
 int nc_server_tls_endpt_del_ctn(const char *endpt_name, int64_t id, const char *fingerprint, NC_TLS_CTN_MAPTYPE map_type, const char *name);
 
-#endif /* ENABLE_TLS */
+#endif /* NC_ENABLED_TLS */
 
 #endif /* NC_SESSION_SERVER_H_ */