(Merge 3.2) Issue #16367: Fix FileIO.readall() on Windows for files larger than 2 GB.

diff --cc Misc/NEWS
Simple merge

diff --cc Modules/_io/fileio.c
index 6e0bbee6fc55369d77b5786dc7e49c518d2d0851,8ea7c58aa8cd566ab533756199865f9466e1cfc5..ca25209305542bad0cee050afd3559e842fab88f
--- 1/Modules/_io/fileio.c
--- 2/Modules/_io/fileio.c
+++ b/Modules/_io/fileio.c
@@@ -601,14 -556,9 +601,14 @@@ new_buffersize(fileio *self, size_t cur
  static PyObject *
  fileio_readall(fileio *self)
  {
 +#ifdef HAVE_FSTAT
 +    struct stat st;
 +    Py_off_t pos, end;
 +#endif
      PyObject *result;
      Py_ssize_t total = 0;
-     int n;
+     Py_ssize_t n;
 +    size_t newsize;
  
      if (self->fd < 0)
          return err_closed();