HIR Const Evaluate - Fix using the pre-monomorph path for cache lookup, add an assert to catch it earlier.
HIR Const Evaluate - Fix using the pre-monomorph path for cache lookup, add an assert to catch it earlier.

thepowersgang/mrustc,thepowersgang/mrustc,thepowersgang/mrustc,thepowersgang/mrustc,thepowersgang/mrustc