Remove superfluous 'virtual' specifiers in ART.

Remove 'virtual' specifier on methods already bearing the 'override'
specifier.

Test: mmma art
Change-Id: I114930969a5ca048d88de9ecd18e2c6403593e31
diff --git a/runtime/common_runtime_test.h b/runtime/common_runtime_test.h
index bf17e64..a5157df 100644
--- a/runtime/common_runtime_test.h
+++ b/runtime/common_runtime_test.h
@@ -157,11 +157,11 @@
   virtual ~CommonRuntimeTestBase() {}
 
  protected:
-  virtual void SetUp() override {
+  void SetUp() override {
     CommonRuntimeTestImpl::SetUp();
   }
 
-  virtual void TearDown() override {
+  void TearDown() override {
     CommonRuntimeTestImpl::TearDown();
   }
 };