- Refactor the way the WalProposerMain function is called when started
with --sync-safekeepers. The postgres binary now explicitly loads
the 'neon.so' library and calls the WalProposerMain in it. This is
simpler than the global function callback "hook" we previously used.
- Move the WAL redo process code to a new library, neon_walredo.so,
and use the same mechanism as for --sync-safekeepers to call the
WalRedoMain function, when launched with --walredo argument.
- Also move the seccomp code to neon_walredo.so library. I kept the
configure check in the postgres side for now, though.
