Make script(1) a little less broken.

Close the file descriptor to the TTY. There is no reason why the parent
process should keep track of the descriptor. This ensures that the
application inside properly drains the TTY during exit(2).

Reported by:	alfred
MFC after:	2 weeks

usr.bin/script/script.c

@@ -158,6 +158,8 @@ main(int argc, char *argv[])
 	}
 	if (child == 0)
 		doshell(argv);
+	else
+		close(slave);
 
 	if (flushtime > 0)
 		tvp = &tv;