bpo-45582: Write empty pybuilddir.txt on Windows to allow relocatable build directories

[zooba]

https://bugs.python.org/issue45582

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot AMD64 Windows10 3.x has failed when building commit b0b3086.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/all/#builders/146/builds/1536) and take a look at the build logs.
4. Check if the failure is related to this commit (b0b3086) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/all/#builders/146/builds/1536

Summary of the results of the build (if available):

Click to see traceback logs

remote: Enumerating objects: 6, done. remote: Counting objects: 16% (1/6) remote: Counting objects: 33% (2/6) remote: Counting objects: 50% (3/6) remote: Counting objects: 66% (4/6) remote: Counting objects: 83% (5/6) remote: Counting objects: 100% (6/6) remote: Counting objects: 100% (6/6), done. remote: Compressing objects: 16% (1/6) remote: Compressing objects: 33% (2/6) remote: Compressing objects: 50% (3/6) remote: Compressing objects: 66% (4/6) remote: Compressing objects: 83% (5/6) remote: Compressing objects: 100% (6/6) remote: Compressing objects: 100% (6/6), done. remote: Total 6 (delta 0), reused 4 (delta 0), pack-reused 0 
From https://github.com/python/cpython
* branch main -> FETCH_HEAD
Note: checking out 'b0b30862796e97b3f0ee358bcc61d21f0cc98441'.
You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by performing another checkout.
If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -b with the checkout command again. Example:
git checkout -b <new-branch-name>
HEAD is now at b0b3086... [bpo-45582](https://bugs.python.org/issue45582): Write empty pybuilddir.txt on Windows to allow relocatable build directories (GH-29979)
Switched to and reset branch 'main'
Could Not Find D:\buildarea\3.x.bolen-windows10\build\Lib\*.pyc
The system cannot find the file specified.
Could Not Find D:\buildarea\3.x.bolen-windows10\build\PCbuild\python*.zip
ERROR: collect_socket() failed
Traceback (most recent call last):
File "D:\buildarea\3.x.bolen-windows10\build\Lib\test\pythoninfo.py", line 785, in collect_info
collect_func(info_add)
^^^^^^^^^^^^^^^^^^^^^^
File "D:\buildarea\3.x.bolen-windows10\build\Lib\test\pythoninfo.py", line 535, in collect_socketimport socket
^^^^^^^^^^^^^
File "D:\buildarea\3.x.bolen-windows10\build\Lib\socket.py", line 51, in <module>import _socket
^^^^^^^^^^^^^^ModuleNotFoundError: No module named '_socket'ERROR: collect_test_support() failed
Traceback (most recent call last):
File "D:\buildarea\3.x.bolen-windows10\build\Lib\test\pythoninfo.py", line 785, in collect_info
collect_func(info_add)
^^^^^^^^^^^^^^^^^^^^^^
File "D:\buildarea\3.x.bolen-windows10\build\Lib\test\pythoninfo.py", line 627, in collect_test_support
call_func(info_add, 'test_support._is_gui_available', support, '_is_gui_available')
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "D:\buildarea\3.x.bolen-windows10\build\Lib\test\pythoninfo.py", line 73, in call_func
value = func()
^^^^^^
File "D:\buildarea\3.x.bolen-windows10\build\Lib\test\support\__init__.py", line 217, in _is_gui_availableimport ctypes
^^^^^^^^^^^^^
File "D:\buildarea\3.x.bolen-windows10\build\Lib\ctypes\__init__.py", line 8, in <module>from _ctypes import Union, Structure, Array
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ModuleNotFoundError: No module named '_ctypes'
Collection failed: exit with error
Could not find platform dependent libraries <exec_prefix>
Traceback (most recent call last):
File "D:\buildarea\3.x.bolen-windows10\build\Lib\runpy.py", line 196, in _run_module_as_mainreturn _run_code(code, main_globals, None,
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "D:\buildarea\3.x.bolen-windows10\build\Lib\runpy.py", line 86, in _run_codeexec(code, run_globals)
^^^^^^^^^^^^^^^^^^^^^^^
File "D:\buildarea\3.x.bolen-windows10\build\Lib\test\__main__.py", line 1, in <module>from test.libregrtest import main
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "D:\buildarea\3.x.bolen-windows10\build\Lib\test\libregrtest\__init__.py", line 2, in <module>from test.libregrtest.main import main
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "D:\buildarea\3.x.bolen-windows10\build\Lib\test\libregrtest\main.py", line 18, in <module>from test.libregrtest.setup import setup_tests
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "D:\buildarea\3.x.bolen-windows10\build\Lib\test\libregrtest\setup.py", line 109"\N{SMILING FACE WITH SUNGLASSES}",
^SyntaxError: (unicode error) \N escapes not supported (can't load unicodedata module)
Cannot open file 'D:\buildarea\3.x.bolen-windows10\build\test-results.xml' for upload
The system cannot find the file specified.
Could Not Find D:\buildarea\3.x.bolen-windows10\build\PCbuild\python*.zip