Add more BufferHubEventFd tests

It checks that epollfd is able to recieve signaled BufferHubEventFd.
It checks that epollfd is able to receive consecutive signals from
BufferHubEventFd and duplicated BufferHubEventFd.

Test: BufferHub_test
Bug: None
Change-Id: Ia3bf8c56f2e858bb144c37b1daf75bd2c1363da7
1 file changed