(append_string): handle NULL strings by printing `(null)'

git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@9392 ec53bebd-3082-4978-b11e-865c3cabbd6b

lib/roken/snprintf.c

@@ -214,6 +214,9 @@ append_string (struct state *state,
 	       int prec,
 	       int flags)
 {
+    if(arg == NULL)
+	arg = (unsigned char*)"(null)";
+
     if(prec != -1)
 	width -= prec;
     else