Upgrade versions of vendored libs

vendor/github.com/DataDog/zstd/zbuff.h

@@ -1,5 +1,6 @@
+#ifndef USE_EXTERNAL_ZSTD
 /*
- * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
+ * Copyright (c) Yann Collet, Facebook, Inc.
  * All rights reserved.
  *
  * This source code is licensed under both the BSD-style license (found in the
@@ -212,3 +213,5 @@ ZBUFF_DEPRECATED("use ZSTD_initDStream_usingDict") size_t ZBUFF_compressInit_adv
 #if defined (__cplusplus)
 }
 #endif
+
+#endif /* USE_EXTERNAL_ZSTD */