[HarfBuzz] Units of members of hb_glyph_position_t

[Eli Zaretskii]

> From: Behdad Esfahbod <behdad at behdad.org>
> Date: Tue, 28 May 2019 14:46:45 -0400
> Cc: "harfbuzz at lists.freedesktop.org" <harfbuzz at lists.freedesktop.org>
> 
> You pick what value you want to represent one pixel as.  Say, you choose 1024.  Then if you want to render at
> "16px" font size, you set scale to 16*1024.  That's all. 

And then the values of hb_glyph_position_t should be divided by 1024
to produce pixels when using this hb_font_t object?