r24282: Try to fix the occasional Samba4 crash in BASE-BENCH-READWRITE, as

r24282: Try to fix the occasional Samba4 crash in BASE-BENCH-READWRITE, as
seen in particular on opi.

This looked like a Heimdal problem, but I think it was simply that we
didn't do a talloc_reference() to keep tabs on the memory we were
using, and in between obtaining the pointer and using it, it was
assigned to unrelated memory.

Andrew Bartlett
(This used to be commit a650ad8b37d58ba64458a33313714d1abfc4850b)