Pre-compute MIR CFG caches for borrowck and other analyses I was puzzled that https://github.com/rust-lang/rust/pull/142390 introduces additional computations of CFG traversals: borrowck computes them, right? It turns out that borrowck clones the MIR body, so doesn't share its cache with other analyses. This PR: - forces the computation of all caches in `mir_promoted` query; - modifies region renumbering to avoid dropping that cache.