pgsql: Hack pg_ctl to report postmaster's exit status.

Hack pg_ctl to report postmaster's exit status.

Temporarily change pg_ctl so that the postmaster's exit status will
be printed (to the postmaster's stdout). This is to help identify
the cause of intermittent "postmaster exited during a parallel
transaction" failures seen on a couple of buildfarm members. This
change degrades pg_ctl's functionality in a couple of minor ways,
so we'll revert it once we've obtained the desired info.

Discussion: https://postgr.es/m/18537.1570421268@sss.pgh.pa.us

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/6a5084eed49552bfc8859c438c8d74ad09fc5d3f

Modified Files
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src/bin/pg_ctl/pg_ctl.c | 31 ++++++++++++++-----------------
1 file changed, 14 insertions(+), 17 deletions(-)