Use sourcecode for libjuice

thirdparty/libjuice/src/const_time.h

@@ -0,0 +1,18 @@
+/**
+ * Copyright (c) 2021 Paul-Louis Ageneau
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+#ifndef JUICE_CONST_TIME_H
+#define JUICE_CONST_TIME_H
+
+#include <stdint.h>
+#include <stdlib.h>
+
+int const_time_memcmp(const void *a, const void *b, size_t len);
+int const_time_strcmp(const void *a, const void *b);
+
+#endif