[3.12] gh-109615: Fix support test_copy_python_src_ignore() (#109958) (#110340)

[3.12] gh-109615: Fix support test_copy_python_src_ignore() (#109958) (#110340)

* gh-109615: Fix support test_copy_python_src_ignore() (#109958)

Fix the test when run on an installed Python: use "abs_srcdir" of
sysconfig, and skip the test if the Python source code cannot be
found.

* Tools/patchcheck/patchcheck.py, Tools/freeze/test/freeze.py and
  Lib/test/libregrtest/utils.py now first try to get "abs_srcdir"
  from sysconfig, before getting "srcdir" from sysconfig.
* test.pythoninfo logs sysconfig "abs_srcdir".

(cherry picked from commit b89ed9df39851348fbb1552294644f99f6b17d2c)

* gh-109615: Fix support test_copy_python_src_ignore() on WASM (#109970)

Not only check if src_dir exists, but look also for Lib/os.py
landmark.

(cherry picked from commit cc54bcf17b5b5f7681f52baf3acef75b995fa1fd)

* gh-109615: Look for 'Modules' as landmark for test_copy_python_src_ignore (GH-110108)

(cherry picked from commit 20bc5f7c28a6f8a2e156c4a748ffabb5efc7c761)

* gh-109748: Fix again venv test_zippath_from_non_installed_posix() (#110149)

Call also copy_python_src_ignore() on listdir() names.

shutil.copytree(): replace set() with an empty tuple. An empty tuple
becomes a constant in the compiler and checking if an item is in an
empty tuple is cheap.

(cherry picked from commit 0def8c712bb6f66f1081cab71deb3681566b846d)

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Co-authored-by: Steve Dower <steve.dower@python.org>