Add PZstandard to contrib/

contrib/pzstd/utils/Likely.h

@@ -0,0 +1,28 @@
+/**
+ * Copyright (c) 2016-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+ 
+/**
+ * Compiler hints to indicate the fast path of an "if" branch: whether
+ * the if condition is likely to be true or false.
+ *
+ * @author Tudor Bosman (tudorb@fb.com)
+ */
+
+#pragma once
+
+#undef LIKELY
+#undef UNLIKELY
+
+#if defined(__GNUC__) && __GNUC__ >= 4
+#define LIKELY(x) (__builtin_expect((x), 1))
+#define UNLIKELY(x) (__builtin_expect((x), 0))
+#else
+#define LIKELY(x) (x)
+#define UNLIKELY(x) (x)
+#endif