Rollup merge of #65689 - RalfJung:miri-debug, r=Centril
Rollup merge of #65689 - RalfJung:miri-debug, r=Centril

bring back some Debug instances for Miri

These were erroneously removed in https://github.com/rust-lang/rust/pull/65647, but Miri needs them.

r? @Centril Cc @nnethercote @oli-obk

graydon/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust