bug#27427: 26.0.50; Native line numbers lead to display error in company-mode popup

[Eli Zaretskii]

> Cc: alexanderm@web.de, 27427@debbugs.gnu.org
> From: Dmitry Gutov <dgutov@yandex.ru>
> Date: Wed, 21 Jun 2017 05:18:38 +0300
> 
> When the position at bol is interpreted as "column 3", all lines of the 
> rectangle are rendered starting with the fourth character of each line. 

So this is the root cause of the problem.  Is there a reason not to
start rendering from the character whose posn-col-row is 3?