If FormatMessageW() is passed the FORMAT_MESSAGE_FROM_SYSTEM flag without FORMAT_MESSAGE_IGNORE_INSERTS, it will fail if there are insert sequences in the message definition.

Automatically replace
tp_print -> tp_vectorcall_offset
tp_compare -> tp_as_async
tp_reserved -> tp_as_async

Follow-up for #1067


https://bugs.python.org/issue29883

LoadLibrary, GetProcAddress, FreeLibrary and GetModuleHandle acquire the system loader lock. Calling these while holding the GIL will cause a deadlock on the rare occasion that another thread is detaching and needs to destroy its thread state at the same time.

Fix memory leaks in asyncio ProactorEventLoop on overlapped operation
failures.

Changes:

* Implement the tp_traverse slot in the _overlapped.Overlapped type
  to help to break reference cycles and identify referrers in the
  garbage collector.
* Always clear overlapped on failure: not only set type to
  TYPE_NOT_STARTED, but release also resources.

Fix a memory leak in asyncio in the ProactorEventLoop when ReadFile()
or WSASend() overlapped operation fail immediately: release the
internal buffer.

METH_NOARGS functions need only a single argument but they are cast
into a PyCFunction, which takes two arguments.  This triggers an
invalid function cast warning in gcc8 due to the argument mismatch.
Fix this by adding a dummy unused argument.

* Support sendfile on Windows Proactor event loop naively.