Rollup merge of #88216 - kornelski:from_layout_err, r=kennytm
Rollup merge of #88216 - kornelski:from_layout_err, r=kennytm

Don't stabilize creation of TryReserveError instances

#48043 + https://github.com/rust-lang/rust/pull/87993#issuecomment-903189016

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