Remove strict-virtual-specifiers option, since it's enabled everywhere.

tools/clang/plugins/tests/virtual_bodies.cpp

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "virtual_bodies.h"
 
 // Shouldn't warn about method usage in the implementation file.
 class VirtualMethodsInImplementation {
  public:
   virtual void MethodIsAbstract() = 0;
   virtual void MethodHasNoArguments();
   virtual void MethodHasEmptyDefaultImpl() {}
   virtual bool ComplainAboutThis() { return true; }
 };
 
 // Stubs to fill in the abstract method
 class ConcreteVirtualMethodsInHeaders : public VirtualMethodsInHeaders {
  public:
-  virtual void MethodIsAbstract() override {}
+  void MethodIsAbstract() override {}
 };
 
 class ConcreteVirtualMethodsInImplementation
     : public VirtualMethodsInImplementation {
  public:
-  virtual void MethodIsAbstract() override {}
+  void MethodIsAbstract() override {}
 };
 
 // Fill in the implementations
 void VirtualMethodsInHeaders::MethodHasNoArguments() {
 }
 void WarnOnMissingVirtual::MethodHasNoArguments() {
 }
 void VirtualMethodsInImplementation::MethodHasNoArguments() {
 }
 
 int main() {
   ConcreteVirtualMethodsInHeaders one;
   ConcreteVirtualMethodsInImplementation two;
 }