pgsql: pgstat: add pg_stat_have_stats() test helper.

pgstat: add pg_stat_have_stats() test helper.

Will be used by tests committed subsequently.

Bumps catversion (this time for real, the one in 0f96965c658 got lost when
rebasing over 5c279a6d350).

Author: Melanie Plageman <melanieplageman@gmail.com>
Discussion: /messages/by-id/CAAKRu_aNxL1WegCa45r=VAViCLnpOU7uNC7bTtGw+=QAPyYivw@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/ad401664b8012cafb64e8fce33fe40356c5bc686

Modified Files
--------------
src/backend/catalog/system_functions.sql | 2 ++
src/backend/utils/activity/pgstat.c | 10 ++++++++++
src/backend/utils/adt/pgstatfuncs.c | 18 ++++++++++++++++++
src/include/catalog/catversion.h | 2 +-
src/include/catalog/pg_proc.dat | 6 ++++++
src/include/pgstat.h | 2 ++
6 files changed, 39 insertions(+), 1 deletion(-)