pdfium: Fix all -Wdelete-non-virtual-dtor violations on Mac.

fpdfsdk/src/fpdfsave.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
  
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "../include/fsdk_define.h"
 #include "../include/fpdfsave.h"
 #include "../include/fpdfedit.h"
 #if _FX_OS_ == _FX_ANDROID_
 #include "time.h"
 #else
 #include <ctime>
 #endif
 
-class CFX_IFileWrite:public IFX_StreamWrite
+class CFX_IFileWrite FX_FINAL : public IFX_StreamWrite
 {
         
 public:
         CFX_IFileWrite();
         FX_BOOL                         Init( FPDF_FILEWRITE * pFileWriteStruct );
         virtual FX_BOOL         WriteBlock(const void* pData, size_t size);
         virtual void            Release(){};
         
 protected:
         FPDF_FILEWRITE*         m_pFileWriteStruct;
@@ skipping 60 matching lines @@
 {
         return _FPDF_Doc_Save(document, pFileWrite, flags, FALSE , 0);
 }
 
 
 DLLEXPORT FPDF_BOOL STDCALL FPDF_SaveWithVersion(       FPDF_DOCUMENT document,FPDF_FILEWRITE * pFileWrite,
         FPDF_DWORD flags, int fileVersion)
 {
         return _FPDF_Doc_Save(document, pFileWrite, flags, TRUE , fileVersion);
 }