C implementation of unpickler.  UnpicklingError is now raised instead of
AttributeError and ValueError in some cases.

glob module; they are now about 3--6 times faster.

Issue #27928: Add scrypt (password-based key derivation function) to hashlib module (requires OpenSSL 1.1.0).

Issue #27960: Revert state to 675e20c38fdac6, backing out all changes by developed for Issue #12885.

Directly pass NULL rather than an empty string.

Don't pass "()" format to PyObject_CallXXX() to call a function without
argument: pass NULL as the format string instead. It avoids to have to parse a
string to produce 0 argument.