Fix fork shared memory access

[DL6ER]

What does this implement/fix?

When adding the three new shared memory objects for client, domain, and DNS cache lookup tables, we forgot to add the code ensuring they are remapped in all processes in case one process has to resize them to add further records. This resulted in TCP forks still trying to access the memory on the previous location where the object is no more present and will inevitable lead to memory corruption, possibly affecting other code regions (such as the very memory allocation intense sqlite3 library) or cause simple crashes due to trying to access non-allocated memory regions.

This PR fixes this and has been confirmed in #2112. Heavy TCP DNS activity was required to see this crash which is probably why it has neither been found during the reviewing process nor by the extensive CI testing suite.

The code in this PR has already been confirmed in #2112

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Related issue or feature (if applicable): Fixes #2112

Pull request in docs with documentation (if applicable): N/A

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