top: fix two potential 'alternate display mode' abends
This commit will address potential abends upon leaving
the windows help or color mapping screens and invoking
alternate display mode ('A'). It only happens if that
current window was changed with multiple 'a'/'w' keys.
So now, rather than leaving a trail of negative values
in the 'begtask' field, compliments of that win_select
function, we'll remove the mkVIZrow1 macro. Henceforth
it will be issued just once per user interaction. Thus
a promise of 'Curwin' only being impacted is restored.
[ my thanks to Vladimir Chren for reporting this bug ]