Fix some memory leaks.

* src/named-ref.c: Add a pointer check (named_ref_free).
	* src/scan-code.l: New function (variant_table_free). Called in
	code_scanner_free.
	* src/symlist.c: Call to named_ref_free (symbol_list_free).

src/symlist.c

@@ -146,7 +146,14 @@ symbol_list_prepend (symbol_list *list, symbol_list *node)
 void
 symbol_list_free (symbol_list *list)
 {
-  LIST_FREE (symbol_list, list);
+  symbol_list *node, *next;
+  for (node = list; node; node = next)
+    {
+      next = node->next;
+      if (node->named_ref)
+        named_ref_free (node->named_ref);
+      free (node);
+    }
 }