1. Add close guard
2. Adopt instead of clone the ahsmem fd to fix a dangling fd
3. Clear only the return flag when writing fd to parcel
4. Immediately destroy remote MemoryIntArray if stale
5. Throw Java exception if someone closed the fd under us
Change-Id: I85533fec336c40e3380e10d5448e18c9616ec341
9d723d3d57