pgsql: Fix full-table-vacuum request mechanism for MultiXactIds

Fix full-table-vacuum request mechanism for MultiXactIds

While autovacuum dutifully launched anti-multixact-wraparound vacuums
when the multixact "age" was reached, the vacuum code was not aware that
it needed to make them be full table vacuums. As the resulting
partial-table vacuums aren't capable of actually increasing relminmxid,
autovacuum continued to launch anti-wraparound vacuums that didn't have
the intended effect, until age of relfrozenxid caused the vacuum to
finally be a full table one via vacuum_freeze_table_age.

To fix, introduce logic for multixacts similar to that for plain
TransactionIds, using the same GUCs.

Backpatch to 9.3, where permanent MultiXactIds were introduced.

Andres Freund, some cleanup by Álvaro

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/f54106f77e6d71cbb3fa0924095e5142341fde2b

Modified Files
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src/backend/access/transam/multixact.c | 15 ++++++++
src/backend/commands/cluster.c | 13 ++++---
src/backend/commands/vacuum.c | 62 +++++++++++++++++++++++---------
src/backend/commands/vacuumlazy.c | 18 +++++++---
src/include/access/multixact.h | 2 ++
src/include/commands/vacuum.h | 5 +--
6 files changed, 87 insertions(+), 28 deletions(-)