pgsql: Fix option argument lookup in in-tree getopt_long().

Fix option argument lookup in in-tree getopt_long().

The in-tree getopt_long() moves each non-option to the end of argv,
which might put it right where an option's argument lookup expects
to find the argument. For example, "vacuumdb postgres --jobs"
takes "postgres" as the number of jobs instead of complaining that
--jobs is missing its argument. To fix, stop the argument lookups
at the start of the moved non-options, which we already track to
know when to stop scanning.

Oversight in commit 411b720343.

Author: Sehrope Sarkuni <sehrope(at)jackdb(dot)com>
Reviewed-by: solai v <solai(dot)cdac(at)gmail(dot)com>
Discussion: https://postgr.es/m/CAH7T-arxDuVCSkorO%3Dk7%2BM-_JV0JFzMpN_EtKMyD2K0RDqZ2OA%40mail.gmail.com
Backpatch-through: 17

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/237176b7951539fcc54f6a81ce1f29853099c3f7

Modified Files
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src/bin/scripts/t/100_vacuumdb.pl | 4 ++++
src/port/getopt_long.c | 14 +++++++-------
2 files changed, 11 insertions(+), 7 deletions(-)