Rollup of 5 pull requests Successful merges: - #129195 (Stabilize `&mut` (and `*mut`) as well as `&Cell` (and `*const Cell`) in const) - #130118 (move Option::unwrap_unchecked into const_option feature gate) - #130295 (Fix target-cpu fpu features on Armv8-R.) - #130371 (Correctly account for niche-optimized tags in rustc_transmute) - #130381 (library: Compute Rust exception class from its string repr) r? `@ghost` `@rustbot` modify labels: rollup