EXTENSIONS : Remove usage of DBG_CTOR and DBG_DTOR.

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

Change-Id: Ied33afa8b32149b6b7b1c0725167349e817d6c89
Reviewed-on: https://gerrit.libreoffice.org/8407
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>