pgsql: Avoid casting away const in sepgsql's quote_object_name.

Avoid casting away const in sepgsql's quote_object_name.

quote_identifier's API is designed on the assumption that it's
not worth worrying about a short-term memory leak when we have
to produce a quoted version of the given identifier.  Whoever wrote
quote_object_name took it on themselves to override that judgment,
but the only way to do so is to cast away const someplace.  We can
avoid that and substantially shorten the function by going along
with quote_identifier's opinion.  AFAICS quote_object_name is not
used in any way where this would be unsustainable.

Per discussion of commit 45987aae2, which exposed that we had
a casting-away-const situation here.

Discussion: https://postgr.es/m/20220827112304.GL2342@telsasoft.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/94077df1c2def788f888a27ed0035236f806466d

Modified Files
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contrib/sepgsql/label.c | 33 ++++++---------------------------
1 file changed, 6 insertions(+), 27 deletions(-)