pg_dumpall: Fix handling of incompatible options.

pg_dumpall: Fix handling of incompatible options.

This commit teaches pg_dumpall to fail when both --clean and
--data-only are specified.  Previously, it passed the options
through to pg_dump, which would fail after pg_dumpall had already
started producing output.  Like recent commits b2898baaf7 and
7c8280eeb5, no back-patch.

Author: Mahendra Singh Thalor <mahi6run@gmail.com>
Reviewed-by: Srinath Reddy Sadipiralla <srinath2133@gmail.com>
Discussion: https://postgr.es/m/CAKYtNArrHiJ0LDB9BFZiUWs6tC78QkBN50wiwO07WhxewYDS3Q%40mail.gmail.com