[gnome-db] MySQL provider doesn't honor authorization outside DNS

[Nicola Fontana <ntd entidi it>]

Sorry to bother again: this one took me some time.

After updating to libgda-3.99.5 I was unable to connect to my
old DSN, any attempt was failing with no useful informations:

$ gda-test-connection-4.0 -s tachet
** (gda-test-connection-4.0:7130): WARNING **: Can't open
connection to DSN tachet: No description

After diving into the sources I found the MySQL provider takes
user/password only from the DNS string. In my old config file I
used <entry name="Username" ...> and <entry name="Password" ...>
so moving them into <entry name="DSN" ...> solved this issue.

As a collateral effect, the auth_string parameter in
gda_connection_open_from_dsn is not honored (tested). I don't
know if this is expected, but there's some inconsistency between
documentation and implementation.

Ciao
-- 
Nicola