SWDEV-458943 - Implement std::mutex based monitor

Implement std::mutex based monitor that has much
simpler logics than legacy monitor.
Create DEBUG_CLR_USE_STDMUTEX_IN_AMD_MONITOR to
toggle them.
If DEBUG_CLR_USE_STDMUTEX_IN_AMD_MONITOR = false
  (by default), use legacy monitor;
If DEBUG_CLR_USE_STDMUTEX_IN_AMD_MONITOR = true,
  use std::mutex based monitor.
If no perf drop of stl::mutex based monitor,
legacy one will be removed later.

Change-Id: I1d21368ff462477d3238d71e4e2a1a7d6b9167ad

rocclr/platform/command.hpp

@@ -183,7 +183,7 @@ class Event : public RuntimeObject {
 
   //! Signal all threads waiting on this event.
   void signal() {
-    ScopedLock lock(lock_);
+    ScopedLock lock(lock_);// Unnecessary
     lock_.notifyAll();
   }