Don't use O_SYNC or similar when opening signal file to fsync it.
No need to use get_sync_bit() when we're calling pg_fsync() on the file.
We're not writing to the files, so it doesn't make any difference in
practice, but seems less surprising this way.
Reviewed-by: Andres Freund
Discussion: https://www.postgresql.org/message-id/
b3b71061-4919-e882-4857-
27e370ab134a%40iki.fi