BUG #5699: Postgres runs only under default user.

The following bug has been logged online:

Bug reference:      5699
Logged by:          Johannes Meidert
Email address:      johannes.meidert@rohde-schwarz.com
PostgreSQL version: 9.0.1
Operating system:   windows
Description:        Postgres runs only under default user.
Details:

If a --superaccount is specified during installation other than 'postgres',
the service will not start correctly and there are lots of errors "role
<postgres> does not exist" in the DB error log.
The option -- superaccount should be removed.

Work around: use postgres and add the user later.