[llvm] [ADT] Add a missing call to a unique_function destructor after move (PR #98747)

[David Blaikie via llvm-commits]

dwblaikie wrote:

Could you add a unit test for this?

A custom functor with a destructor that sets a flag or something, then checking that flag is raised in the right situation?

https://github.com/llvm/llvm-project/pull/98747