In order to allow fetching result of multiple result sets at time same
time, all the data is fetched and copied on demand from the mysql result
set. The mysql result set (MYSQL_RES) is freed afterwards.

That means we need a copy of the meta information as well. Now all the
meta data is stored in the driver for each result set, so it does not
depend on the MYSQL_RES structure anymore.

Also add test case for invoking some meta data queries before and after
fetching the result set.

Change-Id: Ie8bf993926ebe89cd362ab0b311d1f3d164b84df
Reviewed-on: https://gerrit.libreoffice.org/65855Reviewed-by: Andras Timar <andras.timar@collabora.com>
Tested-by: Andras Timar <andras.timar@collabora.com>