CI: `tests/mir-opt`: `64bit-panic-abort` is seemingly not tested

[GrigorenkoPV]

#154004 moved core::ptr::Alignment to core::mem, but seems to have missed updating some of the mir-opt tests, which were fixed #154577.

Curious, why does this test pass against main after the rename? 🤔

But still, this PR only changes the diff, not the rs file. So, it seems like 64bit-panic-abort mir-opt is simply not checked at all by CI.

Originally posted by @RalfJung in #154577 (comment)

[RalfJung]

#154004 moved core::ptr::Alignment to core::mem, but seems to have missed updating some of the mir-opt tests,

Specifically, some of the diff files were no updated. (The rs files were all fine.)
And, notably, bors accepted the PR anyway. That shouldn't have happened.