I don't know that's about - there's no call to GetOldestXmin() in pgstatapprox and pg_visibility after patch 0002? And similarly, the PROCARRAY_* references are also removed in the same patch?
Maybe need to remove them from these places, not?
C:\dll\postgres\contrib>grep -d GetOldestXmin *.c File pgstattuple\pgstatapprox.c: OldestXmin = GetOldestXmin(rel, PROCARRAY_FLAGS_VACUUM); File pg_visibility\pg_visibility.c: OldestXmin = GetOldestXmin(NULL, PROCARRAY_FLAGS_VACUUM); * deadlocks, because surely GetOldestXmin() should never take RecomputedOldestXmin = GetOldestXmin(NULL, PROCARRAY_FLAGS_VACUUM);