pgsql: Small tidyup for commit d41a178b.

Small tidyup for commit d41a178b.

A comment was left behind claiming that we needed to use malloc() rather
than palloc() because the corresponding free would run in another
thread, but that's not true anymore. Remove that comment. And, with
the reason being gone, we might as well actually use palloc().

Back-patch to supported releases, like d41a178b.

Discussion: https://postgr.es/m/CA%2BhUKG%2BpdM9v3Jv4tc2BFx2jh_daY3uzUyAGBhtDkotEQDNPYw%40mail.gmail.com

Branch
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REL_12_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/6f508b8bce2ed66eef310e1b77a84ce1cd222aeb

Modified Files
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src/backend/postmaster/postmaster.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)