Double free in `OwnedAlloc::drop_in_place` when the contained value's `Drop` panics

Summary

`OwnedAlloc::drop_in_place` destroys the contained value by hand, then commits the ownership transfer with `mem::forget(self)` — which lives inside `into_raw` and so runs only after the destruction. `T::drop` is user code and may panic. If it does, the forget is skipped and the still-live `OwnedAlloc` unwinds, whose destructor drops the same `T` a second time and then deallocates. For a `T` that owns an allocation, the same block is freed twice — a double free (CWE-415). That destructor also reads the already-destroyed value through `Layout::for_value` before deallocating, a use-after-free (CWE-416).

`MaybeUninitAlloc::drop_in_place` delegates to the same function, so both public entry points are affected. Storing a value whose `Drop` can panic and calling either is enough — no `unsafe` on the caller's side.

## Fix

No fixed release is available. The crate has had no release since 2018 and the maintainer has not responded to the report, nor to the one on `lockfree`, which is published from the same account. `forget_inner` leaks the value instead of destroying it, which is safe.