Use override to Mark Overriden Methods

When willingly overriding a virtual method, it is good
practice to mark the method with `override`.
Most other places already do so.

Author: ChristianTackeGSI

examples/MQ/serialization/1-simple/Ex1Sampler.h

@@ -63,7 +63,7 @@ class Ex1Sampler : public FairMQDevice
         }
     }
 
-    void Reset()
+    void Reset() override
     {
         if (fInputFile) {
             fInputFile->Close();

examples/MQ/serialization/2-multipart/Ex2Sampler.h

@@ -75,7 +75,7 @@ class Ex2Sampler : public FairMQDevice
         }
     }
 
-    void Reset()
+    void Reset() override
     {
         if (fInputFile) {
             fInputFile->Close();