pgsql: Fix incorrect printing of queries with duplicated join names.

Fix incorrect printing of queries with duplicated join names.

Given a query in which multiple JOIN nodes used the same alias
(which'd necessarily be in different sub-SELECTs), ruleutils.c
would assign the JOIN nodes distinct aliases for clarity ...
but then it forgot to print the modified aliases when dumping
the JOIN nodes themselves. This results in a dump/reload hazard
for views, because the emitted query is flat-out incorrect:
Vars will be printed with table names that have no referent.

This has been wrong for a long time, so back-patch to all supported
branches.

Philip Dubé

Discussion: https://postgr.es/m/CY4PR2101MB080246F2955FF58A6ED1FEAC98140@CY4PR2101MB0802.namprd21.prod.outlook.com

Branch
------
REL9_5_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/bf612fd3a4d8ff4953f400deccc3c8d1e411e935

Modified Files
--------------
src/backend/utils/adt/ruleutils.c | 10 ++++++++-
src/test/regress/expected/create_view.out | 35 +++++++++++++++++++++++++++++++
src/test/regress/sql/create_view.sql | 9 ++++++++
3 files changed, 53 insertions(+), 1 deletion(-)