StableMir doesn't map reexported fn to the original one

[zjp-CN]

As a example in #10 :

{
  "def_id": "DefId { id: 22, name: \"std::ptr::drop_in_place\" }",
  "func": "pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T)"
}

drop_in_place is declared in core lib, but the call name seems to come from the call context.

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Also report this in kani's repo: model-checking/kani#4012