New comment by ericonr on void-packages repository

https://github.com/void-linux/void-packages/pull/26962#issuecomment-739426628

Comment:
```
[  1%] Running generator for QtCore...
shiboken: "/usr/aarch64-linux-musl/usr/include" does not exist.
Command line: --generator-set=shiboken --enable-parent-ctor-heuristic --enable-pyside-extensions --enable-return-value-heuristic --use-isnull-as-nb_nonzero /builddir/pyside-setup-opensource-src-5.15.2/sources/pyside2/build/PySide2/QtCore_global.h --include-paths=/builddir/pyside-setup-opensource-src-5.15.2/sources/pyside2/PySide2:/usr/aarch64-linux-musl/usr/include/qt5/:/usr/aarch64-linux-musl/usr/include/qt5/:/usr/aarch64-linux-musl/usr/include/qt5/QtCore:/usr/aarch64-linux-musl/usr/../usr/lib/qt5//mkspecs/linux-g++:/usr/aarch64-linux-musl/usr /usr/aarch64-linux-musl/usr/include --typesystem-paths=/builddir/pyside-setup-opensource-src-5.15.2/sources/pyside2/build/PySide2:/builddir/pyside-setup-opensource-src-5.15.2/sources/pyside2/PySide2:/builddir/pyside-setup-opensource-src-5.15.2/sources/pyside2/PySide2/QtCore --output-directory=/builddir/pyside-setup-opensource-src-5.15.2/sources/pyside2/build/PySide2/QtCore --license-file=/builddir/pyside-setup-opensource-src-5.15.2/sources/pyside2/PySide2/QtCore/../licensecomment.txt /builddir/pyside-setup-opensource-src-5.15.2/sources/pyside2/build/PySide2/QtCore/typesystem_core.xml --api-version=5.15 --drop-type-entries=
make[2]: *** [PySide2/QtCore/CMakeFiles/QtCore_generator.dir/build.make:87: PySide2/QtCore/mjb_rejected_classes.log] Error 1
```

I have no idea what this cross failure means, the directory should 100% exist.

Besides that, looking good! I like the test additions as well :)