top: give inspect display page algorithm a small boost

top: give inspect display page algorithm a small boost

This commit improves display performance when the user
has scrolled horizontally past the end of a top 'row'.

We can avoid the need to memset our buffer with spaces
and putp those spaces individually by exploiting logic
that already exists. If one '\n' character is inserted
into the buffer instead, the next terminfo string sent
will be Cap_clr_eol achieving exactly the same effect!

(now that we know a '.' + 2 spaces is squeezed to one)
(everything's perfectly justified, but it's just luck)

Signed-off-by: Jim Warner <james.warner@comcast.net>