pgsql: Make replace_relid() leave argument unmodified

Make replace_relid() leave argument unmodified

There are a lot of situations when we share the same pointer to a Bitmapset
structure across different places.  In order to evade undesirable side effects
replace_relid() function should always return a copy.

Reported-by: Richard Guo
Discussion: https://postgr.es/m/CAMbWs4_wJthNtYBL%2BSsebpgF-5L2r5zFFk6xYbS0A78GKOTFHw%40mail.gmail.com
Reviewed-by: Richard Guo, Andres Freund, Ashutosh Bapat, Andrei Lepikhov

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/e0477837ce49d73c9f21a5e00143b741ce6e1f89

Modified Files
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src/backend/optimizer/plan/analyzejoins.c | 11 ++++++++---
src/test/regress/expected/join.out        | 15 +++++++++++++++
src/test/regress/sql/join.sql             |  6 ++++++
3 files changed, 29 insertions(+), 3 deletions(-)