Citing https://www.postgrespro.ru/list/id/E1kfzRR-0001EH-Ph@gemulon.postgresql.org
fixing the same problem:
We previously put the -isysroot switch only into CPPFLAGS, theorizing
that it was only needed to find the right copies of include files.
However, it seems that we also need to use it while linking programs,
to find the right stub ".tbd" files for libraries.  We got away
without that up to now, but apparently that was mostly luck.  It may
also be that failures are only observed when the Xcode version is
noticeably out of sync with the host macOS version; the case that's
prompting action right now is that builds fail when using latest Xcode
(12.2) on macOS Catalina, even though it's fine on Big Sur.

Specifically, the problem arises for `preadv' and `pwritev' (new in MacOS 11 Big Sur) when building with XCode 12.4 (supporting Big Sur) in MacOS 10.15 Catalina.

Use tclConfig.sh/tkConfig.sh for future-proofing
3.14.0 doesn't detect Tcl/Tk with external libtommath, have to do it ourselves

Tcl/Tk 9.0 support was added in 3.13.0b3 and is not official as of 3.14.0;
the build with Homebrew version fails as of this writing

Fixes warnings "configure: WARNING: unrecognized options: --with-tcltk-libs, --with-tcltk-includes"

fix script

Apple CLang excludes it if -isysroot is passed

* Fix specifying XCode SDK for distutils

* Revert to preferring XCode Zlib

It turns out, everything since 2.7.12 and 3.5.2
can use libs from modern XCode SDK
which is always available unless we're using an alternate compiler

Zlib from XCode is virtually always present now so it only makes sense to use it from elsewhere if it's preferred.
Works around build failure for 2.7 that's incapable of using Zlib from XCode 7+ (see #3301)

* use `xcrun` instead of `xcodebuild` which is absent in CLT
* use an alternative way that's compatible with CPython's setup.py since 3.5.2

---------

Co-authored-by: Ivan Pozdeev <vano@mail.mipt.ru>

It breaks the build due to yet unknown structural changes from XCode 15

Did not implement customizable priority due to unclear use feedback and more compilation in the code, can decide and do that separately

Tcl/Tk from MacPorts support is omitted due to CPython's only being compatible with 
Tcl/Tk 9 since 3.12.5 and 3.13.0.

Co-authored-by: Ivan Pozdeev <vano@mail.mipt.ru>

This is now possible because all non-EOL MacOS versions now support
`find -print0`/`sort -z`/`xargs -0`

Mainly for tests, to avoid having to adjust call counts for stubs when the logic changes

Co-authored-by: Ivan Pozdeev <vano@mail.mipt.ru>

add test to test all the flag types

missed some of the changes

* Skip building bundled OpneSSL unnecessary parts
* Remove bundled OpneSSL build hack: no longer needed

More tailored for the emergent internal use cases

also just use extglob everywhere

* Add CPython 3.14-dev
* Update 3.13-dev branch to 3.13
* Use OpenSSL 3.3.0