Issue #18942: sys._debugmallocstats() output was damaged on Windows.

_PyDebugAllocatorStats() called PyOS_snprintf() with a %zd format
code, but MS doesn't support that code.  Interpolated
PY_FORMAT_SIZE_T in place of the "z".
Nerge 3.3 into default.

Issue #18942: sys._debugmallocstats() output was damaged on Windows.

_PyDebugAllocatorStats() called PyOS_snprintf() with a %zd format
code, but MS doesn't support that code.  Interpolated
PY_FORMAT_SIZE_T in place of the "z".
Improve urlencode docstring. Patch by Brian Brazil.
merge from 3.3

Improve urlencode docstring. Patch by Brian Brazil.
Closes issue #15350
Issue #1584: Provide options to override default search paths for Tcl and Tk
when building _tkinter.  configure has two new options; if used, both must
be specified:

  ./configure \
      --with-tcltk-includes="-I/opt/local/include" \
      --with-tcltk-libs="-L/opt/local/lib -ltcl8.5 -ltk8.5"

In addition, the options can be overridden with make:

   make \
       TCLTK_INCLUDES="-I/opt/local/include" \
       TCLTK_LIBS="-L/opt/local/lib -ltcl8.6 -ltk8.6"
Issue #15663: Tcl/Tk 8.5.14 is now included with the OS X 10.6+
64-bit/32-bit installer for 10.6+.  It is no longer necessary
to install a third-party version of Tcl/Tk 8.5 to work around the
problems in the Apple-supplied Tcl/Tk 8.5 shipped in OS X 10.6
and later releases.
Issue #18939: Updated venv documentation with some clarifications.
Closes #18939: Merged documentation update from 3.3.
Issue #18940: Handled low-volume logging when delay is True.
Closes #18940: Merged fix from 3.3.
Issue #18941: Respected delay when doing rollover.
Closes #18941: Merged fix from 3.3.
Issue #18849: Fixed a Windows-specific tempfile bug where collision with an
existing directory caused mkstemp and related APIs to fail instead of
retrying. Report and fix by Vlad Shcherbina.
Issue #18849: Fixed a Windows-specific tempfile bug where collision with an
existing directory caused mkstemp and related APIs to fail instead of
retrying. Report and fix by Vlad Shcherbina.
Issue #18920: argparse's default version action (for -v, --version) should
output to stdout, matching the 'python -v'

Reported by Wolfgang Maier
Update whatsnew/3.4 wrt. --version going to stdout. #18338, #18920, #18922
Close #18924:  Block naive attempts to change an Enum member.
#18852: Handle readline.__doc__ being None in site.py readline activation.

Patch by Berker Peksag.
Issue #18623: Factor out the _SuppressCoreFiles context manager into test.support.
Patch by Valerie Lambert.
Issue #18934: Relax test_multiprocessing.test_invalid_handles a bit: we just
want to check that Connection.poll() doesn't crash.