pgsql: pg_upgrade: warn about extensions that need updating

pg_upgrade: warn about extensions that need updating

Also create a script that can be run to update them.

Reported-by: Dave Cramer

Discussion: /messages/by-id/CADK3HHKawwbOcGwMGnDuAf3-U8YfvTcS8jqDv3UM=niijs3MMA@mail.gmail.com

Backpatch-through: 9.6

Branch
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REL_14_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/4051a7775752bb6643b2fef45f30142b65726b1a

Modified Files
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src/bin/pg_upgrade/check.c | 2 ++
src/bin/pg_upgrade/pg_upgrade.h | 1 +
src/bin/pg_upgrade/version.c | 78 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 81 insertions(+)