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

tools/clang/plugins/tests/base_refcounted.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 "base_refcounted.h"
 
 #include <cstddef>
 
 namespace {
 
 // Unsafe; should error.
 class AnonymousDerivedProtectedToPublicInImpl
     : public ProtectedRefCountedVirtualDtorInHeader {
  public:
   AnonymousDerivedProtectedToPublicInImpl() {}
-  virtual ~AnonymousDerivedProtectedToPublicInImpl() {}
+  ~AnonymousDerivedProtectedToPublicInImpl() override {}
 };
 
 // Unsafe; but we should only warn on the base class.
 class AnonymousDerivedProtectedOnDerived
     : public ProtectedRefCountedDtorInHeader {
  protected:
   ~AnonymousDerivedProtectedOnDerived() {}
 };
 
 }  // namespace
@@ skipping 43 matching lines @@
   PublicRefCountedThreadSafeDtorInHeader another_bad_variation;
   AnonymousDerivedProtectedToPublicInImpl and_this_is_bad_too;
   ImplicitDerivedProtectedToPublicInHeader bad_yet_again;
   UnsafeTypedefChainInImpl and_again_this_is_bad;
 
   WebKitPublicDtorInHeader ignored;
   WebKitDerivedPublicDtorInHeader still_ignored;
 
   return 0;
 }