MINOR: pollers: add a new flag to indicate pollers reporting ERR & HUP

In practice it's all pollers except select(). It turns out that we're
keeping some legacy code only for select and enforcing it on all
pollers, let's offer the pollers the ability to declare that they
do not need that.

include/types/fd.h

@@ -162,7 +162,8 @@ struct fdinfo {
  *  - flags indicate what the poller supports (HAP_POLL_F_*)
  */
 
-#define HAP_POLL_F_RDHUP 0x00000001                          /* the poller notifies of HUP with reads */
+#define HAP_POLL_F_RDHUP        0x00000001                   /* the poller notifies of HUP with reads */
+#define HAP_POLL_F_ERRHUP       0x00000002                   /* the poller reports ERR and HUP */
 
 struct poller {
 	void   *private;                                     /* any private data for the poller */

src/ev_epoll.c

@@ -360,7 +360,7 @@ static void _do_register(void)
 
 	p->name = "epoll";
 	p->pref = 300;
-	p->flags = 0;
+	p->flags = HAP_POLL_F_ERRHUP; // note: RDHUP might be dynamically added
 	p->private = NULL;
 
 	p->clo  = __fd_clo;

src/ev_evports.c

@@ -422,7 +422,7 @@ static void _do_register(void)
 
 	p->name = "evports";
 	p->pref = 300;
-	p->flags = 0;
+	p->flags = HAP_POLL_F_ERRHUP;
 	p->private = NULL;
 
 	p->clo  = NULL;

src/ev_kqueue.c

@@ -358,7 +358,7 @@ static void _do_register(void)
 
 	p->name = "kqueue";
 	p->pref = 300;
-	p->flags = HAP_POLL_F_RDHUP;
+	p->flags = HAP_POLL_F_RDHUP | HAP_POLL_F_ERRHUP;
 	p->private = NULL;
 
 	p->clo  = NULL;

src/ev_poll.c

@@ -328,7 +328,7 @@ static void _do_register(void)
 
 	p->name = "poll";
 	p->pref = 200;
-	p->flags = 0;
+	p->flags = HAP_POLL_F_ERRHUP;
 	p->private = NULL;
 
 	p->clo  = __fd_clo;