update for rustc changes: treat new MIR commands as NOP
update for rustc changes: treat new MIR commands as NOP

aidancully/rust,rust-lang/miri,GBGamer/rust,GBGamer/rust,GBGamer/rust,rust-lang/miri,aidancully/rust,GBGamer/rust,graydon/rust,GBGamer/rust,rust-lang/miri,rust-lang/miri,tsion/miri,aidancully/rust,GBGamer/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,GBGamer/rust,graydon/rust,graydon/rust,GBGamer/rust,aidancully/rust