Windows CI on Github Actions is breaking nondeterministically

[elliottslaughter]

Here's what I see on the Actions dashboard right now:

master has not changed in this time frame, so this is all running the same commit (2cc1cd9). In other words, the issue is non-deterministic, or at least inconsistent. But when it occurs, it appears that no amount of rerunning fixes it.

The failures all exhibit the same failure mode. Windows breaks in one of its two configurations with the message:

437 tests passed. 113 tests failed.

The errors are bizarre, things so basic that it shouldn't be possible to break. The only hint I can see of what's going on is:

error: unknown target CPU 'generic'

Full log from a failing run: 9_Build (windows-2022, llvm-11, cuda=1, luajit).txt

[elliottslaughter]

Appears to have been resolved by #650. I'll reopen if it comes back.