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/class_linker_test.cc b/runtime/class_linker_test.cc
index 52ddd13..ab7182a 100644
--- a/runtime/class_linker_test.cc
+++ b/runtime/class_linker_test.cc
@@ -450,7 +450,7 @@
 
 class ClassLinkerMethodHandlesTest : public ClassLinkerTest {
  protected:
-  virtual void SetUpRuntimeOptions(RuntimeOptions* options) override {
+  void SetUpRuntimeOptions(RuntimeOptions* options) override {
     CommonRuntimeTest::SetUpRuntimeOptions(options);
   }
 };