Fix compiler warnings: explicit cast to int in sha256/sha512 modules
Use Py_intptr_t to store the difference between two pointers, instead of int

Fix a compiler warning on Windows 64-bit
#16523: improve attrgetter/itemgetter/methodcaller documentation.
#16523: merge with 3.3.
#17877: skip test if the Olson's TZ database is missing.
#17877: merge with 3.3.
Issue #1545463: At shutdown, defer finalization of codec modules so that stderr remains usable.

(should fix Windows buildbot failures on test_gc)
Issue #17807: Generators can now be finalized even when they are part of a reference cycle.
Issue #17912: Use a doubly linked-list for thread states.