Fix race condition when CRL checking is enabled.

crypto/stack/stack.c

@@ -331,3 +331,10 @@ void sk_sort(STACK *st)
 		st->sorted=1;
 		}
 	}
+
+int sk_is_sorted(const STACK *st)
+	{
+	if (st)
+		return 1;
+	return st->sorted;
+	}