MINOR: poll/epoll: move detection of RDHUP support earlier

Let's move the detection of support for RDHUP earlier and out of the
FD update chain, as it complicates its simplification.
diff --git a/src/ev_epoll.c b/src/ev_epoll.c
index 330c38c..8810b77 100644
--- a/src/ev_epoll.c
+++ b/src/ev_epoll.c
@@ -222,6 +222,9 @@
 		e = epoll_events[count].events;
 		fd = epoll_events[count].data.fd;
 
+		if ((e & EPOLLRDHUP) && !(cur_poller.flags & HAP_POLL_F_RDHUP))
+			_HA_ATOMIC_OR(&cur_poller.flags, HAP_POLL_F_RDHUP);
+
 #ifdef DEBUG_FD
 		_HA_ATOMIC_INC(&fdtab[fd].event_count);
 #endif
@@ -245,9 +248,6 @@
 		    ((e & EPOLLHUP)   ? FD_EV_SHUT_RW : 0) |
 		    ((e & EPOLLERR)   ? FD_EV_ERR_RW  : 0);
 
-		if ((e & EPOLLRDHUP) && !(cur_poller.flags & HAP_POLL_F_RDHUP))
-			_HA_ATOMIC_OR(&cur_poller.flags, HAP_POLL_F_RDHUP);
-
 		fd_update_events(fd, n);
 	}
 	/* the caller will take care of cached events */