brought back functionality from previous builds but now cross-platform

tier1/utlmutex.cpp

@@ -0,0 +1,22 @@
+#include "tier1/utlmutex.h"
+#include "pthread.h"
+
+CUtlLock::CUtlLock()
+{
+	pthread_mutex_init(&m_lock);
+};
+
+CUtlLock::~CUtlLock()
+{
+	
+};
+
+void CUtlLock::Lock()
+{
+
+};
+
+void CUtlLock::Unlock()
+{
+
+};