CID 1054818: Resource leak in object (CTOR_DTOR_LEAK)

1. alloc_new: Allocating memory by calling "new khmer::SubsetPartition(this)".
   	2. var_assign: Assigning: "this->partition" = "new khmer::SubsetPartition(this)".
   	3. ctor_dtor_leak: The constructor allocates field "partition" of "khmer::Hashbits" but the destructor and whatever functions it calls do not free it.