ncd: add static string "<none>"

ncd/NCDStringIndex.c

@@ -74,7 +74,8 @@ static const char *static_strings[] = {
     "_arg18",
     "_arg19",
     "true",
-    "false"
+    "false",
+    "<none>"
 };
 
 static NCD_string_id_t do_get (NCDStringIndex *o, const char *str, size_t str_len)

ncd/static_strings.h

@@ -55,7 +55,8 @@ enum {
     NCD_STRING_ARG18,
     NCD_STRING_ARG19,
     NCD_STRING_TRUE,
-    NCD_STRING_FALSE
+    NCD_STRING_FALSE,
+    NCD_STRING_NONE
 };
 
 #endif