merge multi threading to master branch

- updated zstd to latest devel release
- lz4, lz5 and zstd is included now
- all three support threading

C/zstdmt/threading.c

@@ -0,0 +1,71 @@
+
+/**
+ * Copyright (c) 2016 Tino Reichardt
+ * 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.
+ *
+ * You can contact the author at:
+ * - zstdmt source repository: https://github.com/mcmilk/zstdmt
+ */
+
+/**
+ * This file will hold wrapper for systems, which do not support Pthreads
+ */
+
+#ifdef _WIN32
+
+/**
+ * Windows Pthread Wrapper, based on this site:
+ * http://www.cse.wustl.edu/~schmidt/win32-cv-1.html
+ */
+
+#include "threading.h"
+
+#include <process.h>
+#include <errno.h>
+
+static unsigned __stdcall worker(void *arg)
+{
+	pthread_t *thread = (pthread_t *) arg;
+	thread->arg = thread->start_routine(thread->arg);
+	return 0;
+}
+
+int
+pthread_create(pthread_t * thread, const void *unused,
+	       void *(*start_routine) (void *), void *arg)
+{
+	(void)unused;
+	thread->arg = arg;
+	thread->start_routine = start_routine;
+	thread->handle =
+	    (HANDLE) _beginthreadex(NULL, 0, worker, thread, 0, NULL);
+
+	if (!thread->handle)
+		return errno;
+	else
+		return 0;
+}
+
+int _pthread_join(pthread_t * thread, void **value_ptr)
+{
+	if (!thread->handle)
+		return 0;
+
+	DWORD result = WaitForSingleObject(thread->handle, INFINITE);
+	switch (result) {
+	case WAIT_OBJECT_0:
+		if (value_ptr)
+			*value_ptr = thread->arg;
+		return 0;
+	case WAIT_ABANDONED:
+		return EINVAL;
+	default:
+		return GetLastError();
+	}
+}
+
+#endif