Fix memory leak in UnwinderFromPid object.

Actually make the destructor virtual so that objects in
UnwinderFromPid get freed.

Also, explicitly make the DexFiles and JitDebug destructors virtual.

Bug: 123099840

Test: Ran UnwindTest.local_from_pid thousands of times.
Change-Id: I8bf11c0eb3587fa82f5f14f4723ea5c91da0fd46
3 files changed