Add HidlMemory

HidlMemory is a wrapper class to support sp<> for hidl_memory. It
also provides a factory method to create an instance of the 'ashmem'
hidl_memory from a opened file descriptor. The number of factory
methods can be increase to support other type of hidl_memory without
break the ABI.

Change-Id: I18176aecdde1c5c1e10582a4a2e87fe466730e17
Bug: 67758915
Test: with the master branch on the Pixel phone.
2 files changed