Bug#24509 - 2048 file descriptor limit on windows needs increasing, also 
WL#3049 - improved Windows I/O
                        
The patch replaces the use of the POSIX I/O interfaces in mysys on Windows with 
the Win32 API calls (CreateFile, WriteFile, etc). The Windows HANDLE for the open 
file is stored in the my_file_info struct, along with a flag for append mode 
because the Windows API does not support opening files in append mode in all cases)
The default max open files has been increased to 16384 and can be increased further
by setting --max-open-files=<value> during the server start.
                              
Another major change in this patch that almost all Windows specific file IO code
has been moved to a new file my_winfile.c, greatly reducing the amount of code 
in #ifdef blocks within mysys, thus improving readability.
                               
                                    
Minor enhancements:
- my_(f)stat() is changed to use __stati64 structure with  64 file size
and timestamps. It will return correct file size now (C runtime implementation
used to report outdated information)
- my_lock on Windows is prepared to handle additional timeout parameter
- after review : changed __WIN__ to _WIN32 in the new and changed code.

client/mysqlbinlog.cc:
  fileno -> my_fileno
client/readline.cc:
  fileno -> my_fileno
include/config-win.h:
  Increase OS_FILE_LIMIT for Windows.
  Remove O_SHARE - Windows does not support it. Its definition conflicts with
  O_SHORT_LIVED, that has different semantics.
include/my_dir.h:
  Use stat64 for stat() family of functions on Windows, because of 64 bit file size.
include/my_global.h:
  Increased default value for open file limit to 16K
include/my_sys.h:
  - my_file_info got new structure members - file handle and open flags
  - 2 new Windows-only mysys functions : my_get_osfhandle and my_osmaperr,
    modelled after Windows C runtime functions _get_osfhandle and _dosmaperr
libmysql/CMakeLists.txt:
  new files my_winfile.c and my_winerr.c
mysql-test/suite/large_tests/r/lock_tables_big.result:
  test for more then 2048 open file descriptors on Windows
mysql-test/suite/large_tests/t/lock_tables_big.test:
  test for more then 2048 open file descriptors on Windows
mysys/CMakeLists.txt:
  new files my_winfile.c and my_winerr.c
mysys/Makefile.am:
  new files my_winfile.c and my_winerr.c
mysys/default_modify.c:
  fileno -> my_fileno
mysys/my_chsize.c:
  implementation of chsize on Windows now moved to my_winfile.c
mysys/my_create.c:
  - my_sopen->my_win_open
  - close open file before removing (won't generally work on Windows otherwise)
mysys/my_file.c:
  On Windows, files returned by my_open will not start with 0, but 2048 
  (making it simple to detect incompatible mix of CRT and mysys  io functions)
mysys/my_fopen.c:
  fileno->my_win_fileno , fclose->my_win_fclose, fdopen->my_win_fdopen
  Check for legal filename is done by my_win_[f]open functions
mysys/my_fstream.c:
  fileno->my_fileno
mysys/my_lib.c:
  Windows stat() functions are moved to my_winfile.c
mysys/my_lock.c:
  Move Windows code under #ifdef to a separate function win_lock().
  Add a parameter for lock wait timeout
mysys/my_mmap.c:
   _get_osfhandle->my_get_osfhandle
mysys/my_open.c:
  my_sopen->my_win_open (simpler interface)
mysys/my_pread.c:
  moved most windows specific code to my_win_file.c
  Use my_win_pread
mysys/my_quick.c:
  Use my_win_read/my_win_write
mysys/my_read.c:
  Moved most of windows specific code to my_win_file.c
  Use my_win_read()
mysys/my_seek.c:
  On Windows, use my_win_lseek() in my_seek()/my_tell()
  Removed dead code (synchronization of lseeks)
  Improved DBUG tracing (file position is ulonglong, not ulong)
mysys/my_static.c:
  Removed array initialization. my_file_info_default is global variable
  thus it is initialized with all zeros anyway
mysys/my_sync.c:
  _commit->my_win_fsync
mysys/my_winerr.c:
  New file my_winerr.c
  Exports my_osmaperr modelled after undocumented C runtime
  function _dosmaperr(). The problem with _dosmaperr() used previously is that 
  1) it is nowhere documented and thus code relying on it is not guaranteed to work
     in subsequent releases on the C runtime
  2) it is present only in static C runtime (mysqld does not link if compiled with
    /MD)
mysys/my_winfile.c:
  New file my_winfile.c
  Implements ANSI/Posix file IO routines, when possible using native Windows IO, without
  C runtime (C runtime dropped because of the 2048 file descriptor limit).
mysys/my_write.c:
  write->my_win_write
mysys/mysys_priv.h:
  Declaration of Windows Posix functions (private to mysys, shall not be visible
  outside)
storage/innobase/handler/ha_innodb.cc:
  mysys native Windows IO : correct innodb tmp file handling
  mysql_tmpfile does not return valid CRT file descriptor, thus
  it is not possible to dup() it. Instead, the native file handle has 
  to be duplicated and then converted to CRT descriptor.
storage/myisam/mi_locking.c:
  _commit->my_sync