pgsql: pg_upgrade: check for clean server shutdowns

pg_upgrade: check for clean server shutdowns

Previously pg_upgrade checked for the pid file and started/stopped the
server to force a clean shutdown. However, "pg_ctl -m immediate"
removes the pid file but doesn't do a clean shutdown, so check
pg_controldata for a clean shutdown too.

Diagnosed-by: Vimalraj A

Discussion: /messages/by-id/CAFKBAK5e4Q-oTUuPPJ56EU_d2Rzodq6GWKS3ncAk3xo7hAsOZg@mail.gmail.com

Backpatch-through: 9.3

Branch
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REL_10_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/9a13e7f0f0c932c06fb459f497be1d83b0916613

Modified Files
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src/bin/pg_upgrade/controldata.c | 59 ++++++++++++++++++++++++++++++++++++++++
src/bin/pg_upgrade/pg_upgrade.c | 3 +-
2 files changed, 61 insertions(+), 1 deletion(-)