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

core/include/fxge/fx_font.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_FONT_H_
 #define _FX_FONT_H_
 #ifndef _FXCRT_EXTENSION_
 #include "../../include/fxcrt/fx_ext.h"
@@ skipping 298 matching lines @@
     virtual void                DeleteFont(void* hFont) = 0;
     virtual void*       RetainFont(void* hFont)
     {
         return NULL;
     }
 };
 class CFX_FolderFontInfo : public IFX_SystemFontInfo
 {
 public:
     CFX_FolderFontInfo();
-    ~CFX_FolderFontInfo();
+    virtual ~CFX_FolderFontInfo();
     void                                AddPath(FX_BSTR path);
     virtual void                Release();
     virtual     FX_BOOL         EnumFontList(CFX_FontMapper* pMapper);
     virtual void*               MapFont(int weight, FX_BOOL bItalic, int charset, int pitch_family, FX_LPCSTR face, FX_BOOL& bExact);
     virtual void*               GetFont(FX_LPCSTR face);
     virtual FX_DWORD    GetFontData(void* hFont, FX_DWORD table, FX_LPBYTE buffer, FX_DWORD size);
     virtual void                DeleteFont(void* hFont);
     virtual     FX_BOOL         GetFaceName(void* hFont, CFX_ByteString& name);
     virtual FX_BOOL             GetFontCharset(void* hFont, int& charset);
 protected:
@@ skipping 89 matching lines @@
 FX_BOOL OutputText(void* dib, int x, int y, CFX_Font* pFont, double font_size,
                    CFX_AffineMatrix* pText_matrix, unsigned short const* text, unsigned long argb);
 class IFX_GSUBTable
 {
 public:
     virtual void        Release() = 0;
     virtual FX_BOOL GetVerticalGlyph(FX_DWORD glyphnum, FX_DWORD* vglyphnum) = 0;
 };
 IFX_GSUBTable* FXGE_CreateGSUBTable(CFX_Font* pFont);
 #endif