pgsql: Lower *_freeze_max_age minimum values.

Lower *_freeze_max_age minimum values.

The old minimum values are rather large, making it time consuming to
test related behaviour. Additionally the current limits, especially for
multixacts, can be problematic in space-constrained systems. 10000000
multixacts can contain a lot of members.

Since there's no good reason for the current limits, lower them a good
bit. Setting them to 0 would be a bad idea, triggering endless vacuums,
so still retain a limit.

While at it fix autovacuum_multixact_freeze_max_age to refer to
multixact.c instead of varsup.c.

Reviewed-By: Robert Haas
Discussion: CA+TgmoYmQPHcrc3GSs7vwvrbTkbcGD9Gik=OztbDGGrovkkEzQ(at)mail(dot)gmail(dot)com
Backpatch: back to 9.0 (in parts)

Branch
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REL9_4_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/4ff753c91bbfb05d56a9ce7517d4bafe3c87b7ce

Modified Files
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src/backend/utils/misc/guc.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)