Add basic tracing functionality

programs/zstdcli_trace.h

@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2016-2021, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+#ifndef ZSTDCLI_TRACE_H
+#define ZSTDCLI_TRACE_H
+
+/**
+ * Enable tracing - log to filename.
+ */
+void TRACE_enable(char const* filename);
+
+/**
+ * Shut down the tracing library.
+ */
+void TRACE_finish(void);
+
+#endif /* ZSTDCLI_TRACE_H */