…hem on exit. (#1908)"

This reverts commit e38d12e.

…hem on exit. (#1908)" (#3337)

This reverts commit e38d12e.

* 'master' of https://github.com/python/cpython: (32 commits)
  Conceptually, roots is a set.  Also searching it as a set is a tiny bit faster (python#3338)
  bpo-31343: Include sys/sysmacros.h (python#3318)
  bpo-30102: Call OPENSSL_add_all_algorithms_noconf (python#3112)
  Prevent a few make suspicious warnings. (python#3341)
  Include additional changes to support blurbified NEWS (python#3340)
  Simplify NEWS entry to prevent suspicious warnings. (python#3339)
  bpo-31347: _PyObject_FastCall_Prepend: do not call memcpy if args might not be null (python#3329)
  Revert "bpo-17852: Maintain a list of BufferedWriter objects.  Flush them on exit. (python#1908)" (python#3337)
  bpo-17852: Maintain a list of BufferedWriter objects.  Flush them on exit. (python#1908)
  Fix terminology in comment and add more design rationale. (python#3335)
  Add comment to explain the implications of not sorting keywords (python#3331)
  bpo-31170: Update libexpat from 2.2.3 to 2.2.4 (python#3315)
  bpo-28411: Remove "modules" field from Py_InterpreterState. (python#1638)
  random_triangular:  sqrt() is more accurate than **0.5 (python#3317)
  Travis: use ccache (python#3307)
  remove IRIX support (closes bpo-31341) (python#3310)
  Code clean-up.  Remove unnecessary pre-increment before the loop starts. (python#3312)
  Regen Moduls/clinic/_ssl.c.h (pythonGH-3320)
  bpo-30502: Fix handling of long oids in ssl. (python#2909)
  Cache externals, depending on changes to PCbuild (python#3308)
  ...

…xit. (python#1908)

* Maintain a list of BufferedWriter objects.  Flush them on exit.

In Python 3, the buffer and the underlying file object are separate
and so the order in which objects are finalized matters.  This is
unlike Python 2 where the file and buffer were a single object and
finalization was done for both at the same time.  In Python 3, if
the file is finalized and closed before the buffer then the data in
the buffer is lost.

This change adds a doubly linked list of open file buffers.  An atexit
hook ensures they are flushed before proceeding with interpreter
shutdown.  This is addition does not remove the need to properly close
files as there are other reasons why buffered data could get lost during
finalization.

Initial patch by Armin Rigo.

* Use weakref.WeakSet instead of WeakKeyDictionary.

* Simplify buffered double-linked list types.

* In _flush_all_writers(), suppress errors from flush().

* Remove NEWS entry, use blurb.

…hem on exit. (python#1908)" (python#3337)

This reverts commit e38d12e.