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_15_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/75e7378f6e15271385d50543a031b1a3bee6be13

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