libbinder: FdTrigger detect read POLLHUP/EOF

> Did you just hang up on me?

>> I don't know, did it sound like this?

*click*

When talking to a service, and it hangs up, don't just stand there, do
something!

Bug: 185167543
Test: binderRpcTest

Change-Id: I5cc00debffad2eb2cca6fabdcf3f55bb69514cb9