ScAddInListener has a member

  ScAddInDocs* pDocs; // documents where this is used

where ScAddInDocs is set<ScDocument*>, and ScDocument has a memmber

  VclPtr<SfxPrinter>    pPrinter;

so that's only a chain of (apparently non-owning) pointers.

Change-Id: I050218320eb2c588dcfaee80225f4e45a515ed32
Reviewed-on: https://gerrit.libreoffice.org/29613Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
Tested-by: Stephan Bergmann <sbergman@redhat.com>