Hold on to the DeckLink configuration object for the entire session, or it...

Hold on to the DeckLink configuration object for the entire session, or it will revert to the defaults in the configuration file. (This change was made during the 7.9 series SDK, it seems.)

This also fixes an issue where VLC would segfault if it could not
initialize the card.

Patch originally by Ed Groth <ed at boxpopuli.com>.

Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>