tubes: fix crash: do not delete boost::shared_ptr's pointer
tubes: fix crash: do not delete boost::shared_ptr's pointer

This prevents a crash on exit for INTERCEPT=demo but there is another:
Open more calc documents, close one, and then type something -> crash.
I wonder if this was working in the past.

Change-Id: I599b1babb02488d317c6684aba7431b5de7af15b

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core