pgsql: Fix failing Memoize test on 32-bit machines

Fix failing Memoize test on 32-bit machines

609f969f6 reduced memory overheads for storing a tuple in Memoize. That
resulted in a Memoize eviction test no longer evicting anything from the
cache on 32-bit machines.

Here we fix that by adding another column to store in the cached
MinimalTuple.

Reported-by: Michael Paquier <michael(at)paquier(dot)xyz>
Discussion: https://postgr.es/m/aof8KwoXaqOBFR_D@paquier.xyz

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/7788fcf39bf98c3403f052f3edd73d86fe1501a7

Modified Files
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src/test/regress/expected/memoize.out | 11 +++++------
src/test/regress/sql/memoize.sql | 2 +-
2 files changed, 6 insertions(+), 7 deletions(-)