Preserve track_caller for by-value dyn vtable shims

[kevin-valerio]

Fixes #157964

[rustbot]

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @folkertdev (or someone else) some time within the next two weeks.

Please see the contribution instructions for more information. Namely, in order to ensure the minimum review times lag, PR authors and assigned reviewers should ensure that the review label (S-waiting-on-review and S-waiting-on-author) stays updated, invoking these commands when appropriate:

• @rustbot author: the review is finished, PR author should check the comments and take action accordingly
• @rustbot review: the author is ready for a review, this PR will be queued again in the reviewer's queue

Why was this reviewer chosen?

The reviewer was selected based on:

• Owners of files modified in this PR: compiler
• compiler expanded to 73 candidates
• Random selection from 20 candidates

[folkertdev]

This makes sense, the previous behavior was really an ABI mismatch I think. Either way it's only observable with unsized_fn_params.

@bors r+ rollup

[rust-bors]

📌 Commit b77dcf4 has been approved by folkertdev

It is now in the queue for this repository.