Fix curses bug: garbled output in nl mode.

Use nonl mode in sl, as more efficient.

src/cmd/sl/sl.c

@@ -90,6 +90,7 @@ int main(int argc, char *argv[])
     initscr();
     signal(SIGINT, SIG_IGN);
     noecho();
+    nonl();
     leaveok(stdscr, TRUE);
     scrollok(stdscr, FALSE);