This necessitates adding d==0 checks in QCollator. By documenting that
moved-from instances can only be assigned to or destroyed, we can
limit the functions in which to check for d==0 to the assignment
operator and the destructor.
Doing otherwise would destroy all advantages of move semantics by
introducing a heap allocation to re-populate other.d.
Add a test for this (QCollator didn't have any before).
Change-Id: Ic6ff202072822bebfd5e48259c3d0fa345a63118
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Marc Mutz