`DBI_TRACE='SQL|pglogin|pgprefix'` has no effect

[KES777]

DBI tries to setup tracing before connecting to database. Thus driver specific options are ignored.

In this case pglogin and pgprefix have no effect.

It would be nice to set debuggig level after DB::driver was parsed
and repeat the call to DBI->trace after that.

How to reproduce:

DBI_TRACE='SQL|pglogin|pgprefix' perl yourscript.pl where you are working with PostgreSQL database.