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.h

@@ -0,0 +1,68 @@
+
+/**
+ * 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
+ */
+
+#ifndef THREADING_H
+#define THREADING_H
+
+#if defined (__cplusplus)
+extern "C" {
+#endif
+
+#ifdef _WIN32
+
+/**
+ * Windows Pthread Wrapper, based on this site:
+ * http://www.cse.wustl.edu/~schmidt/win32-cv-1.html
+ */
+
+#ifndef WIN32_LEAN_AND_MEAN
+#define WIN32_LEAN_AND_MEAN
+#endif
+#include <windows.h>
+
+/* mutex */
+#define pthread_mutex_t CRITICAL_SECTION
+#define pthread_mutex_init(a,b)   InitializeCriticalSection((a))
+#define pthread_mutex_destroy(a)  DeleteCriticalSection((a))
+#define pthread_mutex_lock        EnterCriticalSection
+#define pthread_mutex_unlock      LeaveCriticalSection
+
+/* pthread_create() and pthread_join() */
+typedef struct {
+	HANDLE handle;
+	void *(*start_routine) (void *);
+	void *arg;
+} pthread_t;
+
+extern int pthread_create(pthread_t * thread, const void *unused,
+			  void *(*start_routine) (void *), void *arg);
+
+#define pthread_join(a, b) _pthread_join(&(a), (b))
+extern int _pthread_join(pthread_t * thread, void **value_ptr);
+
+/**
+ * add here more systems as required
+ */
+
+#else
+
+/* POSIX Systems */
+#include <pthread.h>
+
+#endif /* POSIX Systems */
+
+#if defined (__cplusplus)
+}
+#endif
+
+#endif				/* PTHREAD_H */