Remove implicit cast from CFX_ByteString to (const char*).

core/fxcrt/fx_basic_gcc.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 <cctype>
 #include <cwctype>
 #include <limits>
 
@@ skipping 115 matching lines @@
 }
 #ifdef __cplusplus
 }
 #endif
 #endif
 #if _FXM_PLATFORM_ != _FXM_PLATFORM_WINDOWS_
 #ifdef __cplusplus
 extern "C" {
 #endif
 FXSYS_FILE* FXSYS_wfopen(const FX_WCHAR* filename, const FX_WCHAR* mode) {
-  return FXSYS_fopen(CFX_ByteString::FromUnicode(filename),
-                     CFX_ByteString::FromUnicode(mode));
+  return FXSYS_fopen(CFX_ByteString::FromUnicode(filename).c_str(),
+                     CFX_ByteString::FromUnicode(mode).c_str());
 }
 char* FXSYS_strlwr(char* str) {
   if (!str) {
     return NULL;
   }
   char* s = str;
   while (*str) {
     *str = FXSYS_tolower(*str);
     str++;
   }
@@ skipping 98 matching lines @@
       buf[wlen] = bstr[i];
     }
     wlen++;
   }
   return wlen;
 }
 #ifdef __cplusplus
 }
 #endif
 #endif