[flang-rt] Get rid of cyclic call chain in ChildIo. (#183369)
This is a follow up on #182635
It was suggested to place `static_assert(std::is_trivially_destructible_c<A>)`
for the `OwningPtr` class. This cannot be done, because there are
non-trivially destructible types used with `OwnerPtr` (e.g. lots of types
that inherit from `IoErrorHandler`, which is not trivially destructible).
This patch brings back the desctructor call into `OwningPtr::delete_ptr`
just to be on the safe side (though, I do not think we had any memory
leaks even without the destructor call), and removes the cyclic
dependency for the `~ChildIo()` caused by `previous_` member.
llvm-project
a7723994 - [flang-rt] Get rid of cyclic call chain in ChildIo. (#183369)
