Fix -Wunused-function warnings on Windows.

core/src/fpdfapi/fpdf_font/fpdf_font_cid.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/fpdfapi/fpdf_module.h"
 #include "../../../include/fpdfapi/fpdf_page.h"
 #include "../../../include/fpdfapi/fpdf_resource.h"
 #include "../../../include/fxge/fx_freetype.h"
@@ skipping 814 matching lines @@
 }
 FX_WORD CPDF_CIDFont::CIDFromCharCode(FX_DWORD charcode) const {
   if (m_pCMap == NULL) {
     return (FX_WORD)charcode;
   }
   return m_pCMap->CIDFromCharCode(charcode);
 }
 FX_BOOL CPDF_CIDFont::IsVertWriting() const {
   return m_pCMap ? m_pCMap->IsVertWriting() : FALSE;
 }
+
+#if _FXM_PLATFORM_ != _FXM_PLATFORM_WINDOWS_
 extern FX_DWORD FPDFAPI_CharCodeFromCID(const FXCMAP_CMap* pMap, FX_WORD cid);
 static FX_DWORD _EmbeddedCharcodeFromUnicode(const FXCMAP_CMap* pEmbedMap,
                                              int charset,
                                              FX_WCHAR unicode) {
   if (charset <= 0 || charset > 4) {
     return 0;
   }
   CPDF_FontGlobals* pFontGlobals =
       CPDF_ModuleMgr::Get()->GetPageModule()->GetFontGlobals();
   const FX_WORD* pCodes = pFontGlobals->m_EmbeddedToUnicodes[charset].m_pMap;
   if (pCodes == NULL) {
     return 0;
   }
   int nCodes = pFontGlobals->m_EmbeddedToUnicodes[charset].m_Count;
   for (int i = 0; i < nCodes; i++) {
     if (pCodes[i] == unicode) {
       FX_DWORD CharCode = FPDFAPI_CharCodeFromCID(pEmbedMap, i);
       if (CharCode == 0) {
         continue;
       }
       return CharCode;
     }
   }
   return 0;
 }
+#endif  // _FXM_PLATFORM_ != _FXM_PLATFORM_WINDOWS_
+
 static FX_WCHAR _EmbeddedUnicodeFromCharcode(const FXCMAP_CMap* pEmbedMap,
                                              int charset,
                                              FX_DWORD charcode) {
   if (charset <= 0 || charset > 4) {
     return 0;
   }
   FX_WORD cid = FPDFAPI_CIDFromCharCode(pEmbedMap, charcode);
   if (cid == 0) {
     return 0;
   }
@@ skipping 780 matching lines @@
     if (middlecode > CID) {
       end = middle - 1;
     } else if (middlecode < CID) {
       begin = middle + 1;
     } else {
       return &Japan1_VertCIDs[middle].a;
     }
   }
   return NULL;
 }