Run this command across the source:
perl -pi.bak -e 's/(20[012][0-9])-20[12][012]/$1-2023/g' `git ls-files`
and remove changes to po{,-docs}/*.po{,t} (these will be regenerated
later when we run 'make dist').
common/mlutils: Unix_utils.StatVFS.statvfs: This commit implements a
full-featured binding for the statvfs(3) function.
We then use this to reimplement the daemon statvfs API in OCaml.
Note that the Gnulib fallback is dropped in this commit. It
previously referenced non-existent field names in the fs_usage struct
so it didn't work. Also it's not necessary as POSIX has supported
statvfs(3) since 2001, it's supported in *BSD, macOS > 10.4, and there
is already a Windows fallback.