Revert "move libthread to libstb-hal"

This reverts commit 95ee7f9e98.

common/mutex_abstraction.h

@@ -0,0 +1,20 @@
+#ifndef _MUTEX_ABSTRACTION_H
+#define _MUTEX_ABSTRACTION_H
+
+#include <pthread.h>
+
+class Mutex
+{
+	pthread_mutex_t mMutex;
+
+	Mutex(const Mutex&);
+	const Mutex& operator=(const Mutex&);
+
+	public:
+		Mutex();
+		virtual ~Mutex();
+		void lock();
+		void unlock();
+};
+
+#endif