PIMutex typedef std::mutex, patch PIMutexLocker, replace volatile by atomic

lib/main/core/piincludes.h

@@ -30,8 +30,8 @@
 #include <mutex>
 
 typedef std::mutex PIMutex;
+//typedef std::lock_guard<std::mutex> PIMutexLocker;
 class PIObject;
-//class PIMutex;
 class PIString;
 class PIByteArray;
 class PIInit;