pgsql: Simplify main waiting loop of the archiver process

Simplify main waiting loop of the archiver process

As coded, the timeout given to WaitLatch() was always equal to
PGARCH_AUTOWAKE_INTERVAL, as time() was called two times repeatedly.
This simplification could have been done in d75288f.

While on it, this adjusts a comment in pgarch.c to describe the archiver
in a more neutral way.

Author: Sravan Kumar, Nathan Bossart
Reviewed-by: Kyotaro Horiguchi
Discussion: https://postgr.es/m/CA+=NbjjqYE9-Lnw7H7DAiS5jebmoMikwZQb_sBP7kgBCn9q6Hg@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/38cc08546459a9052b6ed43cdb28973288db38c6

Modified Files
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src/backend/postmaster/pgarch.c | 32 +++++++++++---------------------
1 file changed, 11 insertions(+), 21 deletions(-)