fix a few linux compilation warnings

core/src/fpdfdoc/doc_basic.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/fpdfdoc/fpdf_doc.h"
 const int nMaxRecursion = 32;
 int CPDF_Dest::GetPageIndex(CPDF_Document* pDoc)
 {
@@ skipping 232 matching lines @@
         return NULL;
     }
     if (pValue->GetType() == PDFOBJ_ARRAY) {
         return (CPDF_Array*)pValue;
     }
     if (pValue->GetType() == PDFOBJ_DICTIONARY) {
         return ((CPDF_Dictionary*)pValue)->GetArray(FX_BSTRC("D"));
     }
     return NULL;
 }
+#if _FXM_PLATFORM_  == _FXM_PLATFORM_APPLE_ ||  _FXM_PLATFORM_  == _FXM_PLATFORM_WINDOWS_
 static CFX_WideString ChangeSlashToPlatform(FX_LPCWSTR str)
 {
     CFX_WideString result;
     while (*str) {
         if (*str == '/') {
 #if _FXM_PLATFORM_  == _FXM_PLATFORM_APPLE_
             result += ':';
 #elif _FXM_PLATFORM_  == _FXM_PLATFORM_WINDOWS_
             result += '\\';
 #else
             result += *str;
 #endif
         } else {
             result += *str;
         }
         str++;
     }
     return result;
 }
+static CFX_WideString ChangeSlashToPDF(FX_LPCWSTR str)
+{
+    CFX_WideString result;
+    while (*str) {
+        if (*str == '\\' || *str == ':') {
+            result += '/';
+        } else {
+            result += *str;
+        }
+        str++;
+    }
+    return result;
+}
+#endif
 static CFX_WideString FILESPEC_DecodeFileName(FX_WSTR filepath)
 {
     if (filepath.GetLength() <= 1) {
         return CFX_WideString();
     }
 #if _FXM_PLATFORM_  == _FXM_PLATFORM_APPLE_
     if (filepath.Left(sizeof("/Mac") - 1) == CFX_WideStringC(L"/Mac")) {
         return ChangeSlashToPlatform(filepath.GetPtr() + 1);
     }
     return ChangeSlashToPlatform(filepath.GetPtr());
@@ skipping 60 matching lines @@
 FX_BOOL CPDF_FileSpec::IsURL() const
 {
     if (m_pObj == NULL) {
         return FALSE;
     }
     if (m_pObj->GetType() != PDFOBJ_DICTIONARY) {
         return FALSE;
     }
     return ((CPDF_Dictionary*)m_pObj)->GetString(FX_BSTRC("FS")) == FX_BSTRC("URL");
 }
-static CFX_WideString ChangeSlashToPDF(FX_LPCWSTR str)
-{
-    CFX_WideString result;
-    while (*str) {
-        if (*str == '\\' || *str == ':') {
-            result += '/';
-        } else {
-            result += *str;
-        }
-        str++;
-    }
-    return result;
-}
 CFX_WideString FILESPEC_EncodeFileName(FX_WSTR filepath)
 {
     if (filepath.GetLength() <= 1) {
         return CFX_WideString();
     }
 #if _FXM_PLATFORM_  == _FXM_PLATFORM_WINDOWS_
     if (filepath.GetAt(1) == ':') {
         CFX_WideString result;
         result = '/';
         result += filepath.GetAt(0);
@@ skipping 188 matching lines @@
     if (nPage > 0 && nPage <= nPages) {
         return nPage;
     }
     return -1;
 }
 FX_INT32 CPDF_PageLabel::GetPageByLabel(FX_WSTR wsLabel) const
 {
     CFX_ByteString bsLabel = PDF_EncodeText((CFX_WideString)wsLabel);
     return GetPageByLabel(bsLabel);
 }