libbinder: BBinder::attachObject abort on OOM

This API doesn't really work in an OOM situation (even before the return
type was changed to a void*). Since we don't actually need or want to be
handling these situations gracefully in userspace Android, changing it
to an abort.

Bug: 192023359
Test: N/A
Change-Id: I8b7405bceb528e11a194c0d659d365975107b53f