pgsql: Replace getopt() with our re-entrant variant in the backend

Replace getopt() with our re-entrant variant in the backend

Some of these probably could continue using non-re-entrant getopt()
even if we start using threads in the future, but it seems better to
make them all anyway, so that we have a clear-cut rule of "no plain
getopt() in the postgres binary".

Reviewed-by: Peter Eisentraut <peter(at)eisentraut(dot)org>
Discussion: https://www.postgresql.org/message-id/d1da5f0e-0d68-47c9-a882-eb22f462752f@iki.fi

Branch
------
master

Details
-------
https://git.postgresql.org/pg/commitdiff/681774315d738ed9bb213d755c6f39fa5b5009b9

Modified Files
--------------
src/backend/bootstrap/bootstrap.c | 28 +++++++-------
src/backend/postmaster/postmaster.c | 60 +++++++++++++----------------
src/backend/tcop/postgres.c | 77 ++++++++++++++++---------------------
src/backend/utils/misc/ps_status.c | 3 +-
4 files changed, 77 insertions(+), 91 deletions(-)