bpo-28280: Make PyMapping_Keys(), PyMapping_Values() and PyMapping_Items() always return a list (#3840)

With the upgrade of buildbot.python.org from Buildbot 0.8.x to 0.9.x,
the xmlrpc interface has been removed.  This test is now skipped until
it can be rewritten to query a suitable substitute.

See PEP 539 for details.

Highlights of changes:

- Add Thread Specific Storage (TSS) API
- Document the Thread Local Storage (TLS) API as deprecated
- Update code that used TLS API to use TSS API

There just isn't much we can assert in a portable way.

Per PEP 492, 'async' and 'await' should become proper keywords in 3.7.

Implement PEP 553, built-in breakpoint() with support from sys.breakpointhook(), along with documentation and tests.  Closes bpo-31353

Fix test_exception_errpipe_bad_data() and
test_exception_errpipe_normal() of test_subprocess: mock os.waitpid()
to avoid calling the real os.waitpid(0, 0) which is an unexpected
side effect of the test.

sre_compile does bit test (e.g. `flags & SRE_FLAG_IGNORECASE`) in loop.
`IntFlag.__and__` and `IntFlag.__new__` made it slower.

So this commit convert it to normal int before passing flags to `sre_compile()`.

Followed format of other entries.

Implementations of these operations are virtually identical.

* Fix incorrect links.
* Remove redundant links.
* Add signatures and index entries for gettext related
functions in the locale module.

On Windows, Py_FatalError() now limits the size to 256 bytes of the
buffer used to call OutputDebugStringW(). Previously, the size
depended on the length of the error message.

While there is not real bug in this case, using re.IGNORECASE without re.ASCII
leads unexpected behavior.
Instead of adding re.ASCII, this commit removes re.IGNORECASE flag because
it's easier and simpler.

This commit removes dead copy of the pattern in email.util module too.
While the pattern is same, it is compiled separately because it had different flags.

when pass a string larger than 2 GiB.

Decrease memory requirements for Tcl's bigmem tests.

Update the compile tests for optimization levels to also check that
__debug__ blocks are included or excluded based on the optimization
level.
Patch by Diana Clarke.

to integer with binary base.

It shows show import time of each module.
It's useful for optimizing startup time.

Typical usage: python -X importtime -c 'import requests'

On macOS, a process can exit with -SIGKILL if it is killed "early"
with SIGTERM.

On macOS, use uuid_generate_time() instead of
uuid_generate_time_safe() of libuuid, since uuid_generate_time_safe()
is not available.