Issue #16136: VMSError is done, bye bye VMS
Issue #21745: Mention VS2010 SP1 as a solution for LNK1123 errors
Per Martin [1], PGO is no longer used for official releases.

[1] https://mail.python.org/pipermail/python-dev/2014-June/135018.html
Issue #20043: Add direct test for _thread.
Issue #19493: Refactor ctypes test package.

Skipped tests are now marked as skipped, formerly commented-out or
renamed-so-it-doesn't-look-like-a-test tests are uncommented, properly named,
and unconditionally skipped, some tests that simply didn't run before
are now able to run, and a few are split into multiple methods instead of
skipping via 'return' in the middle of a method.  Also, a couple of unused
files are removed completely.
Issue #21726: Remove unnecessary and contextually wrong line.
Issue #21730: Add no-thread skip in test_socket. Patch by Berker Peksag.