Ashmem HIDL Interface Implementation

IAshmem interface is implemented by the Ashmem class in ashmemd.
open passes a hidl_handle containing the open fd to /dev/ashmem
to a call back function. The calling process can copy this
handle to take ownership of the fd.

Change-Id: I73b0466246b0a0b8503abf291ced11fb2673687a
Bug: 133319042
Test: ashmemd_test
4 files changed