initialize and print out constant flag

Author: alandekok

src/lib/unlang/xlat_alloc.c

@@ -39,7 +39,7 @@ xlat_exp_head_t *_xlat_exp_head_alloc(NDEBUG_LOCATION_ARGS TALLOC_CTX *ctx)
 	MEM(head = talloc_zero(ctx, xlat_exp_head_t));
 
 	fr_dlist_init(&head->dlist, xlat_exp_t, entry);
-	head->flags.pure = head->flags.can_purify = true;
+	head->flags.constant = head->flags.pure = head->flags.can_purify = true;
 #ifndef NDEBUG
 	head->file = file;
 	head->line = line;

src/lib/unlang/xlat_tokenize.c

@@ -1006,10 +1006,11 @@ static void _xlat_debug_head(xlat_exp_head_t const *head, int depth)
 
 	fr_assert(head != NULL);
 
-	INFO_INDENT("head flags = %s %s %s",
+	INFO_INDENT("head flags = %s %s %s %s",
 		    head->flags.needs_resolving ? "need_resolving," : "",
 		    head->flags.pure ? "pure" : "",
-		    head->flags.can_purify ? "can_purify" : "");
+		    head->flags.can_purify ? "can_purify" : "",
+		    head->flags.constant ? "constant" : "");
 
 	depth++;