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/scan-code.l

@@ -350,6 +350,15 @@ variant_table_grow ()
   return &variant_table[variant_count - 1];
 }
 
+static void
+variant_table_free ()
+{
+  if (variant_table)
+    free (variant_table);
+  variant_table = 0;
+  variant_table_size = variant_count = 0;
+}
+
 static char *
 find_prefix_end (const char *prefix, char *begin, char *end)
 {
@@ -865,6 +874,8 @@ void
 code_scanner_free (void)
 {
   obstack_free (&obstack_for_string, 0);
+  variant_table_free ();
+
   /* Reclaim Flex's buffers.  */
   yylex_destroy ();
 }