This might actually matter in practice given

https://stackoverflow.com/questions/27422871/does-deletedc-automatically-unselect-objects

"DCs get a default 1x1x1 bitmap when they're created. This will leak if you don't put it back."

Change-Id: Ib2d361995621ad429277ff52cb8c9fdfc0009953
Reviewed-on: https://gerrit.libreoffice.org/38875Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>