should frontend tools use syncfs() ?

Forking this thread in which Thomas implemented syncfs for the startup process
(61752afb2).
https://www.postgresql.org/message-id/flat/CA%2BhUKG%2BSG9jSW3ekwib0cSdC0yD-jReJ21X4bZAmqxoWTLTc2A%40mail.gmail.com

Is there any reason that initdb/pg_basebackup/pg_checksums/pg_rewind shouldn't
use syncfs()  ?

do_syncfs() is in src/backend/ so would need to be duplicated^Wimplemented in
common.

They can't use the GUC, so need to add an cmdline option or look at an
environment variable.