Fix numerous issues with DdmVmInternal allocation tracking

Issues addressed:
- Using without JDWP attached caused native crash.
- When buffer is full (64k entries), number of entries reported was 0.
- Disabling tracking after disabling tracking caused native crash.
- Asking for allocations after disabled caused native crash.
- Lock ordering issues between mutator lock and alloc tracker lock.

Adding 098-ddmc test to cover these cases.

Bug: 17392248

(cherry picked from commit a5815065)

Change-Id: Ib0bc18dfcdafcc050ab9dceed3d167dd878d1d7a