Small rearrangement to bring together the three functions for probing the hash table.
Correct Profile class usage example. Addresses issue #18033.
Patch contributed by Olivier Hervieu and Dmi Baranov.
merge from 3.3

Correct Profile class usage example. Addresses issue #18033.
Patch contributed by Olivier Hervieu and Dmi Baranov.
Close #18952: correctly download test support data

When test.support was converted to a package, it started silently
skipping the tests which needed to download support data to run.

This change refactors the affected code, and also tidies up
test.support.findfile to remove the unused *here* parameter, document
the *subdir* parameter and rename the *filename* parameter to avoid
shadowing the file builtin and be consistent with the documentation.

The unexpected skips were noticed and reported by Zachary Ware
Issue 18808:  blind attempt to repair some buildbot failures.

test_is_alive_after_fork is failing on some old Linux kernels, but
passing on all newer ones.  Since virtually anything can go wrong
with locks when mixing threads with fork, replace the most likely
cause with a redundant simple data member.
Merge #18952 fix from 3.3
Remove the freelist scheme for setobjects.

The setobject freelist was consuming memory but not providing much value.
Even when a freelisted setobject was available, most of the setobject
fields still needed to be initialized and the small table still required
a memset().  This meant that the custom freelisting scheme for sets was
providing almost no incremental benefit over the default Python freelist
scheme used by _PyObject_Malloc() in Objects/obmalloc.c.
Improve code clarity by removing two unattractive macros.
Minor code beautification.
Fix the dead link of IEEE_854-1987 standard with the Wikipedia entry.
Addresses issue #18438
merge from 3.3

Fix the dead link of IEEE_854-1987 standard with the Wikipedia entry.
Addresses issue #18438
Put the defines in the logical section and fix indentation.
Issue #18934: Use poll/select-based selectors for multiprocessing.Connection,
to avoid one extra FD per Connection.
Issue #18963: Fix test_selectors.test_above_fd_setsize on OS X, where the
default RLIMIT_NOFILE hard limit can be RLIMIT_INFINITY.
Close #18957: The PYTHONFAULTHANDLER environment variable now only enables the
faulthandler module if the variable is non-empty. Same behaviour than other
variables like PYTHONDONTWRITEBYTECODE.
Issue #18904: Improve os.get/set_inheritable() tests
Issue #18904: test_socket: add inheritance tests using fcntl and FD_CLOEXEC
Issue #18935: Fix test_regrtest.test_timeout when built --without-threads (the
'--timeout' option requires faulthandler.dump_traceback_later).
Issue #18963: skip test_selectors.test_above_fd_setsize on older OS X versions.
Merge.