Fix package build failure when the compiler types not defined (Fixes #20428)

[pitmanst]

This fixes the install issue #20428 by adding a default value when a compiler type is not defined. While this fix is specifically for z/OS, it should also fix other platforms that have their compiler_type changed in distutils/setuptools such as mingw32.

I tested this with installing the librt package. I've added no testcases as there's no new functionality.

[hauntsaninja]

Thank you!

[ilevkivskyi]

I will sync this to librt (and make a new release) tomorrow, unless @hauntsaninja you want to try doing the librt sync/release.

[hauntsaninja]

Would be open to trying over the weekend!

[ilevkivskyi]

@hauntsaninja Great! I just sent you an invite to mypyc org. Please follow instructions in README in https://github.com/mypyc/librt. If you are not sure about anything, please ask either here or on Discord, I will be around for most of the weekend.

[ilevkivskyi]

@hauntsaninja Are you still interested in doing this?

[hauntsaninja]

Yes! I only got the GitHub invite, not the PyPi invite — meant to ask you about it

[ilevkivskyi]

You don't need any PyPI permissions for this, PyPI publishing is done using trusted publishing.

[hauntsaninja]

Okay great! 0.7.5 is released with this change. Was very straightforward :-)

[pitmanst]

Thank you both - I just tried installing it and it's working great again!