Fix/fix CWIPI virtual function specifiers

This fixes the override/final specifiers in CommMPI and CommCWIPI to allow for compilation with CWIPI enabled.

library/LibUtilities/Communication/CommCwipi.h

@@ -63,14 +63,14 @@ public:
     }
 
     /// Name of class
-    static std::string className;
+    LIB_UTILITIES_EXPORT static std::string className;
 
-    CommCwipi(int narg, char *arg[]);
+    LIB_UTILITIES_EXPORT CommCwipi(int narg, char *arg[]);
 
-    virtual ~CommCwipi();
+    LIB_UTILITIES_EXPORT virtual ~CommCwipi() override;
 
 protected:
-    virtual void v_Finalise();
+    virtual void v_Finalise() final;
 };
 }
 }