if both stdout and stderr are redirected to a non-tty, pledge(2) will kill

if both stdout and stderr are redirected to a non-tty, pledge(2) will kill
ncurses applications, e.g.:

/usr/games/worms 2>&1 | cat

solve this by only calling pledge(2) after initscr(3) is set and done, or
whatever function that calls it. since pledge(2) is called later now the
promises might be reduced, but this a diff for another day.

found by naddy@ almost a year ago, discussed with him deraadt@ and tb@
ok tb@