bug#28936: move_it_in_display_line_to returns MOVE_POS_MATCH_OR_ZV before ZV

[Eli Zaretskii]

> Date: Sat, 21 Oct 2017 22:14:39 -0700
> From: Keith David Bershatsky <esq@lawlist.com>
> 
> Here is a second draft move_it_in_display_line_to_x, with compatibility for 
> word-wrap and also horizontal scrolling the current line that erroneously 
> returns MOVE_LINE_TRUNCATED when trying to reach a target X that is about 
> 1,000 pixels from the beginning of the line.

Once again, please show either a recipe in "emacs -Q" or a stand-alone
code snippet, which demonstrate the issues you mention.  FWIW, I
couldn't find such vulnerabilities by code inspection.