SVX : Remove usage of DBG_CTOR and DBG_DTOR.

Valgrind is capable of detecting such bugs. No need for extra macros.

Change-Id: I9f2ab3703feb5c49a831da124e161f98cb1bb3ab
Reviewed-on: https://gerrit.libreoffice.org/8419
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>