FeatStd Memory Pool

Enforce Initialization of BackingHeap

Initialization of BackingHeap (MallocBackingHeap) is enforced. BackingHeap initializations are reference counted and missing initialization will assert. This is to detect missing initialization early, even if MallocBackingHeap does not require Init (but switching to other BackingHeap will cause crashes then). A new parameter in BackingHeap::Destroy() / MallocBackingHeap::Destroy() forces the destruction of the heap (even if init counter is larger 1).