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

Branch
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master

Details
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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(-)