curs_scroll(3) on FreeBSD

The text f17a3d1592e1, as FreeBSD 2.1.7.1-RELEASE, FreeBSD 2.1.7-RELEASE, FreeBSD 2.1.5-RELEASE, FreeBSD 2.0.5-RELEASE shipped it.

scroll a ncurses window

curs_scroll(3) on FreeBSD now