Investigate why mir-linker test requires an unwind annotation #1978
Description
This is concerned with the mir-linker test (tests/cargo-kani/mir-linker/src/lib.rs).
Before CBMC 5.72.0, this test did not require an unwind annotation.
With CBMC 5.72.0, not specifying an unwind value causes it to unwind forever (see #1941).
Investigate why.