winlink_shuffle_up
idx = winlink_shuffle_up(dst_s, target->wl, before);
idx = winlink_shuffle_up(dst_s, dst_s->curw, before);
idx = winlink_shuffle_up(dst, target.wl, before);
idx = winlink_shuffle_up(dst, dst->curw, before);
idx = winlink_shuffle_up(s, wl, before);
int winlink_shuffle_up(struct session *, struct winlink *, int);