pgsql: Fixes for ChangeVarNodes_walker()

Fixes for ChangeVarNodes_walker()

This commit fixes two bug in ChangeVarNodes_walker() function.

* When considering RestrictInfo, walk down to its clauses based on the
presense of relid to be deleted not just in clause_relids but also in
required_relids.

* Incrementally adjust num_base_rels based on the change of clause_relids
instead of recalculating it using clause_relids, which could contain
outer-join relids.

Reported-by: Richard Guo <guofenglinux(at)gmail(dot)com>
Discussion: https://postgr.es/m/CAMbWs49PE3CvnV8vrQ0Dr%3DHqgZZmX0tdNbzVNJxqc8yg-8kDQQ%40mail.gmail.com
Author: Andrei Lepikhov <lepihov(at)gmail(dot)com>
Reviewed-by: Alexander Korotkov <aekorotkov(at)gmail(dot)com>

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/2260c7f6d90ecf76d3806d32890a0890688b41e8

Modified Files
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src/backend/rewrite/rewriteManip.c | 28 ++++++++++++++++++++++++----
src/test/regress/expected/join.out | 16 +++++++++++++++-
src/test/regress/sql/join.sql | 8 +++++++-
3 files changed, 46 insertions(+), 6 deletions(-)