Fix ODR violation of EventQueueTimer base class

src/lib/base/SimpleEventQueueBuffer.cpp

@@ -20,6 +20,8 @@
 #include "base/Stopwatch.h"
 #include "arch/Arch.h"
 
+class EventQueueTimer { };
+
 //
 // SimpleEventQueueBuffer
 //

src/lib/base/SimpleEventQueueBuffer.h

@@ -50,9 +50,3 @@ private:
     EventDeque            m_queue;
 };
 
-class EventQueueTimer
-{
-public:
-    EventQueueTimer() { }
-    virtual ~EventQueueTimer() { }
-};