Windows testing does not catch path syntax problems when generating files

[gilles-peskine-arm]

#10502 is a bug on Windows which is due to a file generation script printing out a Windows path with backslashes, but that printed path is consumed by CMake which needs a POSIX path with slashes.

Somehow this didn't break our Windows CI.

The goal of this issue is to improve our CI so that this bug (and similar ones) would be caught.

[taraszakharchenkointl]

Somehow this didn't break our Windows CI.

Could be somehow related to cmake version. I didn't test it with the other versions, however. So I am just speculating at this point.