- Bump _yplib_timeout limit from 10 to 20 seconds to better handle

packet loss when talking to a NIS server.
- Set 1 second retry timeout to further realistically handle UDP
  packet loss for yp_next packet bursts.  If the packet hasn't come
  back within 1 second its rather unlikely to come back at all.  There
  is still back-off mechanism in RPC so if there is another reason
  than packet loss for the lack of response within 1 second, the NIS
  server will not be totally bombarded with requests.

This reduces the risk of NIS failing with:

     yp_next: clnt_call: RPC: Timed out

considerably.  This is mainly a problem if you have larger NIS maps
(like at FreeBSD.org) since enumerations of the lists will cause a UDP
packet bursts where a few packets being lost once in a while do
happen.

MFC after:	1 week
Discussed with:	peter
Problem mainly diagnosed by:	peter

lib/libc/yp/yplib.c

@@ -103,7 +103,7 @@ void *ypresp_data;
 static void _yp_unbind(struct dom_binding *);
 struct dom_binding *_ypbindlist;
 static char _yp_domain[MAXHOSTNAMELEN];
-int _yplib_timeout = 10;
+int _yplib_timeout = 20;
 
 static mutex_t _ypmutex = MUTEX_INITIALIZER;
 #define YPLOCK()	mutex_lock(&_ypmutex);
@@ -823,6 +823,14 @@ yp_next(char *indomain, char *inmap, char *inkey, int inkeylen,
 		return (YPERR_DOMAIN);
 	}
 
+	/*
+	 * Set low retry timeout to realistically handle UDP packet
+	 * loss for yp_next packet bursts.
+	 */
+	tv.tv_sec = 1;
+	tv.tv_usec = 0;
+	clnt_control(ysd->dom_client, CLSET_RETRY_TIMEOUT, (char*)&tv);
+
 	tv.tv_sec = _yplib_timeout;
 	tv.tv_usec = 0;