[ft] Misaki Mincho metrics issues

[Nikolay Sivov]

Hello,

I have some troubles with Misaki Mincho font (misakimn.ttf) [1], 
regarding embedded bitmaps metrics.

Looking at EBLC data, there's only one strike available, metrics are:

---
Horizontal Line Metrics
               Ascender:    8
              Descender:    8
---
                 ppem X:     8
                 ppem Y:     8
---

What freetype does in tt_face_load_strike_metrics():

---
metrics->ascender  = (FT_Char)strike[16] * 64;  /* hori.ascender  */
metrics->descender = (FT_Char)strike[17] * 64;  /* hori.descender */
metrics->height    = metrics->ascender - metrics->descender;
---

So resulting 'height' is set to zero, and this eventually leads to 
division by zero in our code.

The question is mostly if it's reasonable to have some kind of 
workaround for that in freetype itself, like ignoring descender entirely 
in such cases or something else?


[1] https://packages.debian.org/jessie/all/fonts-misaki/download