Remove dead Intel intrinsics #3691
Description
Since rust-lang/stdarch#1584 there are some LLVM intel intrinsics that stdarch does not use any more, making them dead code in Miri. Might be a good idea to clean that up. :)
(I also wonder whether there's some good way to check, in the future, that we don't have other dead untested vendor intrinsics... maybe something that checks line coverage or so?)