This patch corrects a couple of minor problems with telnet when using
the notkbd option (-n).

The first issue was to disable changing raw mode when a pipe was being
used.  This would result in raw mode being enabled on the calling
console.

The second issue was a deadlock caused by the net child being handed a
terminal note.  This would cause the parent to spin waiting for the
child to notify.  This was changed to a waitpid loop such that the
main thread can shutdown gracefully if needed.

Reference: /n/sources/patch/maybe/telnet-notkbd
Date: Thu Dec  5 06:09:07 CET 2013
Signed-off-by: sstallion@gmail.com

--- /sys/src/cmd/ip/telnet.c	Thu Dec  5 06:09:02 2013
+++ /sys/src/cmd/ip/telnet.c	Thu Dec  5 06:09:00 2013
@@ -159,12 +159,13 @@
 		netpid = pid;
 		notify(notifyf);
 		fromkbd(net);
-		if(notkbd)
-			for(;;)
-				sleep(1000); // sleep(0) is a cpuhog
+		if(notkbd){
+			while(waitpid() != -1)
+				;
+		}else
+			sendnote(netpid, "die");
 		if (svc)
 			remove(svc);
-		sendnote(netpid, "die");
 		exits(0);
 	}
 }
@@ -323,6 +324,8 @@
 void
 rawon(void)
 {
+	if(notkbd)
+		return;
 	if(debug)
 		fprint(2, "rawon\n");
 	if(consctl < 0)
@@ -340,6 +343,8 @@
 void
 rawoff(void)
 {
+	if(notkbd)
+		return;
 	if(debug)
 		fprint(2, "rawoff\n");
 	if(consctl < 0)