Revert dup2() checking in syslogger.c

Per the expanded comment-

As we're just trying to reset these to go to DEVNULL, there's not
much point in checking for failure from the close/dup2 calls here,
if they fail then presumably the file descriptors are closed and
any writes will go into the bitbucket anyway.

Pointed out by Tom.
Remove orphaned prototype

Rajeev rastogi
Revert C comment change in slot_attisnull()

Revert 89774b58b0ea2874765cae10c094bb6aaf707feb
Update comment.

generate_normalized_query() no longer needs to truncate text, but this
one comment didn't get the memo.  Per Peter Geoghegan.
Add pg_stat_archiver statistics view.

This view shows the statistics about the WAL archiver process's activity.

Gabriele Bartolini, reviewed by Michael Paquier, refactored a bit by me.