pgsql: pg_stat_statements: Fix test that assumes wal_records = rows.

pg_stat_statements: Fix test that assumes wal_records = rows.

It's not very robust to assume that each inserted row will produce
exactly one WAL record and that no other WAL records will be generated
in the process, because for example a particular transaction could
always be the one that has to extend clog.

Because these tests are not run by 'make installcheck' but only by
'make check', it may be that in our current testing infrastructure
this can't be hit, but it doesn't seem like a good idea to rely on
that, since unrelated changes to the regression tests or the way
write-ahead logging is done could easily cause it to start happening,
and debugging such failures is a pain.

Adjust the regression test to be less sensitive.

Anton Melnikov, reviewed by Julien Rouhaud

Discussion: http://postgr.es/m/1ccd00d9-1723-6b68-ae56-655aab00d406@inbox.ru

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/2d7ead85267cc0a41ea4e94ee0ac144d5214d353

Modified Files
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contrib/pg_stat_statements/expected/pg_stat_statements.out | 8 ++++----
contrib/pg_stat_statements/sql/pg_stat_statements.sql | 2 +-
2 files changed, 5 insertions(+), 5 deletions(-)