pgsql: On second thought, the tests for what to do with stderr output

Log Message:
-----------
On second thought, the tests for what to do with stderr output are a
lot more sensible if we check the chunk-output case first. Not
back-patched since it's just a cosmetic improvement.

Modified Files:
--------------
pgsql/src/backend/utils/error:
elog.c (r1.188 -> r1.189)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/error/elog.c.diff?r1=1.188&r2=1.189)