bug#54646: 29.0.50; set-fontset-font and font clipping issues

[Eli Zaretskii]

> From: Visuwesh <visuweshm@gmail.com>
> Cc: rpluim@gmail.com,  54646@debbugs.gnu.org
> Date: Thu, 21 Apr 2022 20:20:45 +0530
> 
> I was not successful in getting the data for all offending sequences.
> The offending sequences were,
> 
> bb9 bbf -- ஹி
> ba9 bc1 -- னு
> bb5 bbf       -- வி
> b86 -- ஆ
> 
> and the GOOD case for bb9 bbf is
> 
>     lbearing 1 rbearing 28 width 28 ascent 9 descent 5
>     1 bb9 bbf xadvance 1809 yadvance 0 xoffset 0 yoffset 0
>     xpos 0 yoff 0 wadjust 28
> 
> and the BAD case is
> 
>     lbearing 1 rbearing 28 width 28 ascent 9 descent 5
>     1 bb9 bbf xadvance 3193 yadvance 0 xoffset 0 yoffset 0
>     xpos 0 yoff 0 wadjust 50

This looks like HarfBuzz is feeding us incorrect data for some reason,
but I cannot imagine what that reason could be, sorry.