fix memory leak in vns

- declare all desctuctor virtual. RefBase should always
  have virtual destructor.
- handle the case of memory release in mocked state properly.
- add debugging capability for memory track to dump.
  should uncomment DBG_MEM_LEAK.
- added alloc / free log for some data.

bug: 31918042

Change-Id: Idbef20f6107232107d618bd2e7e4653ab02ebeb7
9 files changed