Fix -Wnon-virtual-dtor compiler warnings.

core/include/fxge/fx_ge.h

 // 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
 
 #ifndef _FX_GE_H_
 #define _FX_GE_H_
 #ifndef _FX_DIB_H_
 #include "fx_dib.h"
@@ skipping 619 matching lines @@
     virtual int         GetDriverType()
     {
         return 0;
     }
 
     virtual void    ClearDriver() {}
 };
 class IFX_PSOutput
 {
 public:
+    virtual void  Release() = 0;
+    virtual void        OutputPS(FX_LPCSTR string, int len) = 0;
 
-    virtual void        OutputPS(FX_LPCSTR string, int len) = 0;
-    virtual void  Release() = 0;
+protected:
+    ~IFX_PSOutput() { }
 };
 class CPSFont;
 class CFX_PSRenderer : public CFX_Object
 {
 public:
 
     CFX_PSRenderer();
 
     ~CFX_PSRenderer();
 
@@ skipping 71 matching lines @@
 
     void                        SetGraphState(const CFX_GraphStateData* pGraphState);
 
     void                        SetColor(FX_DWORD color, int alpha_flag, void* pIccTransform);
 
     void                        FindPSFontGlyph(CFX_FaceCache* pFaceCache, CFX_Font* pFont, const FXTEXT_CHARPOS& charpos, int& ps_fontnum, int &ps_glyphindex);
 
     void                        WritePSBinary(FX_LPCBYTE data, int len);
 };
 #endif