Use generated shim headers for zlib.

third_party/zlib/contrib/minizip/ioapi.h

 /* ioapi.h -- IO base function header for compress/uncompress .zip
    part of the MiniZip project - ( http://www.winimage.com/zLibDll/minizip.html )
 
          Copyright (C) 1998-2010 Gilles Vollant (minizip) ( http://www.winimage.com/zLibDll/minizip.html )
 
          Modifications for Zip64 support
          Copyright (C) 2009-2010 Mathias Svensson ( http://result42.com )
 
          For more info read MiniZip_info.txt
 
@@ skipping 24 matching lines @@
         #ifndef _LARGEFILE64_SOURCE
                 #define _LARGEFILE64_SOURCE
         #endif
         #ifndef _FILE_OFFSET_BIT
                 #define _FILE_OFFSET_BIT 64
         #endif
 #endif
 
 #include <stdio.h>
 #include <stdlib.h>
-#if defined(USE_SYSTEM_ZLIB)
-#include <zlib.h>
-#else
 #include "third_party/zlib/zlib.h"
-#endif
 
 #if defined(USE_FILE32API)
 #define fopen64 fopen
 #define ftello64 ftell
 #define fseeko64 fseek
 #else
 #ifdef _MSC_VER
  #define fopen64 fopen
  #if (_MSC_VER >= 1400) && (!(defined(NO_MSCVER_FILE64_FUNC)))
   #define ftello64 _ftelli64
@@ skipping 135 matching lines @@
 
 #define ZOPEN64(filefunc,filename,mode)         (call_zopen64((&(filefunc)),(filename),(mode)))
 #define ZTELL64(filefunc,filestream)            (call_ztell64((&(filefunc)),(filestream)))
 #define ZSEEK64(filefunc,filestream,pos,mode)   (call_zseek64((&(filefunc)),(filestream),(pos),(mode)))
 
 #ifdef __cplusplus
 }
 #endif
 
 #endif