Sync OpenBSD patchset 429:
Sync OpenBSD patchset 429:

Now we are correctly not redrawing the whole pane on linefeed, redo the
last-cursor-position code to move to the right position when panes reach EOL.


klaxalk/tmux,klaxalk/tmux,klaxalk/tmux,klaxalk/tmux,klaxalk/tmux