firebird-sdbc: Allow describe-bind for Sqlda wrapper.

Is needed to handle input XSQLDAs.

Change-Id: I7b57dd97e0ff5cebedae245e5a609f2aac1a5820
firebird-sdbc: Sqlda wrapper also needs operator->.

Change-Id: I12a57dff5183365e3b05d107204d593c3d4ca6a6
firebird-sdbc: upgrade PreparedStatement to use Sqlda wrapper.

Change-Id: If79a8b1cfe76292054db4417c452f6443e663fda