PARCELABLE_WRITE_RETURN_VALUE will close the fd when writeParcelable is
called. This is not always preferable (specifically, if
TestNetworkInterface is passed as an "in" parameter).
writeParcelable(FileDescriptor, ...) should therefore use the flags
passed to writeToParcel which should be correct for all cases.
Test: atest EthernetManagerTest
Change-Id: Ibb5f14028a3d686157504da3657a18ec0bc28110
2ebff8a777