Auto merge of #2002 - RalfJung:negative-shifts, r=RalfJung
Auto merge of #2002 - RalfJung:negative-shifts, r=RalfJung

add extra tests for shifts with negative offsets

Cc https://github.com/rust-lang/rust/pull/94659

rust-lang/miri,rust-lang/miri,rust-lang/miri,rust-lang/miri