CI: -Denable-llvm for test-cases

This requires using -Dstatic-llvm and setting the search prefix and the
target, just like it is required for building stage2 and stage3. This
prevents Zig from trying to integrate with the system, which would
trigger an error due to the `cc` command not being installed.

closes #12144
932d1f785eAndrew Kelley committed on 7/29/2022, 6:03:12 PMparenta7a6f38
1 file changedLine totals unavailable