Auto merge of #67260 - TheSamsa:const-limit, r=oli-obk

const limit for CTFE

I tried to tackle the first steps for this issue.
The active feature flag does link to the issue below, I think this has to change, because there should be a tracking issue?
https://github.com/TheSamsa/rust/blob/1679a7647da0de672bac26b716db82d16f3896a8/src/librustc_feature/active.rs#L530

Also, I only put up the storage of the limit like "recursion_limit" but created a seperate file in the same place. Since I guess the invocation happens seperately.
https://github.com/TheSamsa/rust/blob/const-limit/src/librustc/middle/const_limit.rs

If this does not hold up for the issue and since there is a time pressure, just reject it.

hopefully this does not put more load on you than I expected...