Detect "the other" Red Hat patch for Cygwin

[uranusjr]

Another one for #10151 and #10208. This should cover Cygwin users and also provide slightly better detection for Red Hat derivatives, as discussed in #10217.

cc @allenatdecisiv

[allenatdecisiv]

@uranusjr,

I created a Cygwin package with the patch from this PR, here's the source: https://github.com/allenatdecisiv/python-pip-21.2.2-1025.src.

It passed a basic uninstall and re-install of platformdirs. Is there any other testing I could do?

$ cygcheck -c | grep ^python38-pip
python38-pip                  21.2.2-1025                     OK

$ set | grep PIP_
PIP_FORMAT=columns
PIP_NO_COLOR=true

$ command -V pip
pip is hashed (/usr/bin/pip)

$ pip --version
pip 21.2.2.1025 from /usr/lib/python3.8/site-packages/pip (python 3.8)

$ pip uninstall platformdirs
Found existing installation: platformdirs 2.2.0
Uninstalling platformdirs-2.2.0:
  Would remove:
    /usr/local/lib/python3.8/site-packages/platformdirs-2.2.0.dist-info/*
    /usr/local/lib/python3.8/site-packages/platformdirs/*
Proceed (Y/n)? Y
  Successfully uninstalled platformdirs-2.2.0

$ pip install platformdirs
Collecting platformdirs
  Using cached platformdirs-2.2.0-py3-none-any.whl (13 kB)
Installing collected packages: platformdirs
Successfully installed platformdirs-2.2.0

[uranusjr]

I think what you did is enough (for this patch), thanks a ton!