brought back functionality from previous builds but now cross-platform

public/tier1/utlmutex.h

@@ -0,0 +1,21 @@
+#ifndef TIER1_UTL_MUTEX_H
+#define TIER1_UTL_MUTEX_H
+
+#include "pthread.h"
+
+class CUtlLock
+{
+public:
+	CUtlLock();
+	~CUtlLock();
+
+	CUtlLock(const CUtlLock&) = delete;
+	CUtlLock& operator=(const CUtlLock&) = delete;
+
+	void Lock();
+	void Unlock();
+private:
+	pthread_mutex_t m_lock;
+};
+
+#endif