pgsql: pg_upgrade: Don't print progress status when output is not a tty

pg_upgrade: Don't print progress status when output is not a tty.

Until this change pg_upgrade with output redirected to a file / pipe would end
up printing all files in the cluster. This has made check-world output
exceedingly verbose.

Author: Andres Freund <andres@anarazel.de>
Reviewed-By: Justin Pryzby <pryzby@telsasoft.com>
Reviewed-By: Daniel Gustafsson <daniel@yesql.se>
Discussion: https://postgr.es/m/CA+hUKGKjrV61ZVJ8OSag+3rKRmCZXPc03bDyWMqhXg3rdZ=fOw@mail.gmail.com

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/27b02e070fd1b6622b10937d9346b65ffacbc351

Modified Files
--------------
src/bin/pg_upgrade/dump.c        |  2 +-
src/bin/pg_upgrade/option.c      |  2 ++
src/bin/pg_upgrade/pg_upgrade.c  |  2 +-
src/bin/pg_upgrade/pg_upgrade.h  |  2 ++
src/bin/pg_upgrade/relfilenode.c |  6 ++--
src/bin/pg_upgrade/util.c        | 61 ++++++++++++++++++++++++++++++++--------
6 files changed, 59 insertions(+), 16 deletions(-)