Add dummy ssl_tls13_{client,server}.c

Change-Id: Ic1cd1d55b097f5a31c9f48e9d55733d75ab49982
Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/library/Makefile b/library/Makefile
index 0ee6e4f..8c58fb8 100644
--- a/library/Makefile
+++ b/library/Makefile
@@ -167,6 +167,8 @@
 	  ssl_ticket.o \
 	  ssl_tls.o \
 	  ssl_tls13_keys.o \
+	  ssl_tls13_client.o \
+	  ssl_tls13_server.o \
 	  # This line is intentionally left blank
 
 .SILENT: