VCL : Remove usage of DBG_CTOR and DBG_DTOR.

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

Change-Id: I6a785b42be72736560ec69f1a7949f2f0b9414a3
Reviewed-on: https://gerrit.libreoffice.org/6805
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>