pgsql: Fix failure to mark all aggregates with appropriate transtype.

Fix failure to mark all aggregates with appropriate transtype.

In commit 915b703e1 I gave get_agg_clause_costs() the responsibility of
marking Aggref nodes with the appropriate aggtranstype.  I failed to notice
that where it was being called from, it might see only a subset of the
Aggref nodes that were in the original targetlist.  Specifically, if there
are duplicate aggregate calls in the tlist, either make_sort_input_target
or make_window_input_target might put just a single instance into the
grouping_target, and then only that instance would get marked.  Fix by
moving the call back into grouping_planner(), before we start building
assorted PathTargets from the query tlist.  Per report from Stefan Huehner.

Report: <20160702131056.GD3165@huehner.biz>

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/420c1661630c96ad10f58ca967d5f561bb404cf9

Modified Files
--------------
src/backend/optimizer/plan/planner.c | 54 ++++++++++++++++++++++--------------
src/test/regress/expected/limit.out  | 24 ++++++++++++++++
src/test/regress/sql/limit.sql       |  8 ++++++
3 files changed, 65 insertions(+), 21 deletions(-)