minui: events: add ability to poll on non-input fds

Change-Id: Iad52a6f2adcae0068d252d6163586f9d7b93121d
Signed-off-by: Dima Zavin <dima@android.com>
diff --git a/minui/minui.h b/minui/minui.h
index 5a4168c..cb1ed65 100644
--- a/minui/minui.h
+++ b/minui/minui.h
@@ -49,6 +49,7 @@
 
 int ev_init(ev_callback input_cb, void *data);
 void ev_exit(void);
+int ev_add_fd(int fd, ev_callback cb, void *data);
 
 /* timeout has the same semantics as for poll
  *    0 : don't block