sync with plan 9

src/cmd/rc/havefork.c

@@ -1,5 +1,3 @@
-#include <u.h>
-#include <signal.h>
 #include "rc.h"
 #include "getflags.h"
 #include "exec.h"
@@ -13,9 +11,7 @@ Xasync(void)
 {
 	int null = open("/dev/null", 0);
 	int pid;
-	int tcpgrp, pgrp;
 	char npid[10];
-
 	if(null<0){
 		Xerror("Can't open /dev/null\n");
 		return;
@@ -26,12 +22,6 @@ Xasync(void)
 		Xerror("try again");
 		break;
 	case 0:
-		/*
-		 * Should make reads of tty fail, writes succeed.
-		 */
-		signal(SIGTTIN, SIG_IGN);
-		signal(SIGTTOU, SIG_IGN);
-
 		pushredir(ROPEN, null, 0);
 		start(runq->code, runq->pc+1, runq->local);
 		runq->ret = 0;