Remove caching from CVar prefix defines

[Archez]

These should not be cached, it could lead to weird behavior for local dev.

Build Artifacts

• 2ship-linux.zip
• 2ship-mac.zip
• 2ship-windows.zip

[Malkierian]

Do they still work as-is with the rest of it, though? As I recalled, I had trouble with it as anything but cached. The way to reset them in local dev is just with a --fresh in the setup command.

[Malkierian]

The real solution to this, now that I know more about CMake, might just be setting it up with the Option flow instead, but that would also require a change to LUS to match.

[Archez]

Yeah that is the issue here. They should not be cache vars on LUS side, but instead option with defaults, then ports use set like I have here in the PR.

From my testing (confirmed on mac and windows), my cache entry has the "old/bad" values, but with this PR the real values are still used. So this should be good to merged, but in general a PR to LUS is also preferred as well.

Per CMake docs:

Note: The content of the cache variable will not be directly accessible if a normal variable of the same name already exists (see rules of variable evaluation).