Rollup merge of #62295 - RalfJung:miri-realloc, r=cramertj
Rollup merge of #62295 - RalfJung:miri-realloc, r=cramertj

miri realloc: do not require giving old size+align

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