patch 9.2.0744: popup_atcursor() closes immediately on white space

patch 9.2.0744: popup_atcursor() closes immediately on white space

Problem:  popup_atcursor() closes immediately on white space (Mao-Yining)
Solution: Set w_popup_mincol and w_popup_maxcol to the cursor column
          (Yasuhiro Matsumoto)

When the cursor is on white space find_ident_under_cursor() skips forward
to the next word, so the moved range did not cover the cursor column and
popup_check_cursor_pos() closed the popup right away.  Keep the cursor
column in that case.

fixes:  #20652
closes: #20659

Signed-off-by: Yasuhiro Matsumoto <mattn.jp@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>