These belong in libbitcoin_common.a, not libbitcoin_util.a, because they aren’t general-purpose utilities, they just contain some common glue code that is used by both the node and the wallet. Another reason not to include these in libbitcoin_util.a is to prevent them from being used by the kernel library.
Also rename ambiguous MakeHandler functions to MakeCleanupHandler and MakeSignalHandler. Cleanup function handler was introduced after boost signals handler, so original naming didn’t make much sense.
This just contains a move-only commit, and a rename commit. There are no actual code or behavior changes.
This PR is an alternative to #26293, and solves the same issue of removing a boost dependency from the util library. The advantages of this PR compared to #26293 are that it keeps the source directory structure more flat, and it avoids having to change #includes all over the codebase.