Revert "move libthread to libstb-hal"

This reverts commit 95ee7f9e98.

common/mutex_abstraction.cpp

@@ -0,0 +1,22 @@
+#include "mutex_abstraction.h"
+
+Mutex::Mutex() :
+	mMutex()
+{
+	pthread_mutex_init(&mMutex, 0);
+}
+
+Mutex::~Mutex()
+{
+	pthread_mutex_destroy(&mMutex);
+}
+
+void Mutex::lock()
+{
+	pthread_mutex_lock(&mMutex);
+}
+
+void Mutex::unlock()
+{
+	pthread_mutex_unlock(&mMutex);
+}