um: Monitor error events in IRQ controller

Ensure that file closes, connection closes, etc are propagated
as interrupts in the interrupt controller.

Fixes: ff6a1798 ("Epoll based IRQ controller")
Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/um/os-Linux/irq.c

@@ -48,7 +48,7 @@ int os_epoll_triggered(int index, int events)
 int os_event_mask(enum um_irq_type irq_type)
 {
 	if (irq_type == IRQ_READ)
-		return EPOLLIN | EPOLLPRI;
+		return EPOLLIN | EPOLLPRI | EPOLLERR | EPOLLHUP | EPOLLRDHUP;
 	if (irq_type == IRQ_WRITE)
 		return EPOLLOUT;
 	return 0;