fix a few linux compilation warnings

core/src/fpdftext/fpdf_text.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_page.h"
 #include "../../include/fpdfapi/fpdf_pageobj.h"
 #include "../../include/fpdftext/fpdf_text.h"
 #include "txtproc.h"
@@ skipping 130 matching lines @@
         pFont->AppendChar(segment, charcode);
         space_count = 0;
         last_left = char_left;
         last_right = char_right;
     }
     if (segment.GetLength())
         pBaseLine = InsertTextBox(pBaseLine, baseline, leftx + segment_left, leftx + segment_right,
                                   topy, bottomy, spacew, fontsize_v, segment, pFont);
     FX_Free(pPosArray);
 }
-static void ConvertPDFString(CFX_ByteString& result, CFX_ByteString& src, CPDF_Font* pFont);
+
 CTextBaseLine* CTextPage::InsertTextBox(CTextBaseLine* pBaseLine, FX_FLOAT basey, FX_FLOAT leftx,
                                         FX_FLOAT rightx, FX_FLOAT topy, FX_FLOAT bottomy, FX_FLOAT spacew, FX_FLOAT fontsize_v,
                                         CFX_ByteString& str, CPDF_Font* pFont)
 {
     if (str.GetLength() == 0) {
         return NULL;
     }
     if (pBaseLine == NULL) {
         int i;
         for (i = 0; i < m_BaseLines.GetSize(); i ++) {
@@ skipping 619 matching lines @@
 {
     buffer.EstimateSize(0, 10240);
     CPDF_Page page;
     page.Load(pDoc, pPage);
     CPDF_ParseOptions options;
     options.m_bTextOnly = TRUE;
     options.m_bSeparateForm = FALSE;
     page.ParseContent(&options);
     _PDF_GetTextStream_Unicode(buffer, &page, TRUE, NULL);
 }