clang-tidy: Enable cppcoreguidelines-explicit-virtual-functions

Adds override (introduced in C++11) to overridden virtual functions
and removes virtual from those functions as it is not required.

virtual on non base class implementations was used to help indicate
to the user that a function was virtual. C++ compilers did not use
the presence of this to signify an overridden function.

In C++11 override and final keywords were introduced to allow
overridden functions to be marked appropriately. Their presence
allows compilers to verify that an overridden function correctly
overrides a base class implementation.

This can be useful as compilers can generate a compile time error
when:
- The base class implementation function signature changes.
- The user has not created the override with the correct signature.

Signed-off-by: George Liu <liuxiwei@ieisystem.com>
Change-Id: I428f69c11b071a1a50e7f93f7bcc29c8300dcddb
diff --git a/test/mocked_association_interface.hpp b/test/mocked_association_interface.hpp
index 0ad4796..ff25861 100644
--- a/test/mocked_association_interface.hpp
+++ b/test/mocked_association_interface.hpp
@@ -7,7 +7,7 @@
 class MockedAssociationInterface : public AssociationInterface
 {
   public:
-    virtual ~MockedAssociationInterface() = default;
+    ~MockedAssociationInterface() override = default;
 
     MOCK_METHOD1(createActiveAssociation, void(const std::string& path));
     MOCK_METHOD1(addFunctionalAssociation, void(const std::string& path));