Missing fonts issue with GNU Icecat

[Daniel Gerber]

Hi guix,

I have a profile with icecat, fontconfig and basic fonts, but the 
browser seems not to find any font. It displays only 
numbers-in-squares placeholders.

```
$ icecat
(/gnu/store/x9c8vysvvivx4bc1xa4gz7sl37y3i2k6-icecat-60.3.0-gnu1/lib/icecat/.icecat-real:3240): 
Pango-WARNING **: 10:16:13.107: failed to create cairo scaled 
font, expect ugly output. the offending font is 'DejaVu Sans 
9.9990234375'
(/gnu/store/x9c8vysvvivx4bc1xa4gz7sl37y3i2k6-icecat-60.3.0-gnu1/lib/icecat/.icecat-real:3240): 
Pango-WARNING **: 10:16:13.107: font_face status is: file not 
found
(/gnu/store/x9c8vysvvivx4bc1xa4gz7sl37y3i2k6-icecat-60.3.0-gnu1/lib/icecat/.icecat-real:3240): 
Pango-WARNING **: 10:16:13.108: scaled_font status is: file not 
found
(/gnu/store/x9c8vysvvivx4bc1xa4gz7sl37y3i2k6-icecat-60.3.0-gnu1/lib/icecat/.icecat-real:3240): 
Pango-WARNING **: 10:16:13.108: shaping failure, expect ugly 
output. shape-engine='PangoFcShapeEngine', font='DejaVu Sans 
9.9990234375', text='●'
(/gnu/store/x9c8vysvvivx4bc1xa4gz7sl37y3i2k6-icecat-60.3.0-gnu1/lib/icecat/.icecat-real:3240): 
Pango-WARNING **: 10:16:13.113: failed to create cairo scaled 
font, expect ugly output. the offending font is 'DejaVu Sans 
9.9990234375'
(/gnu/store/x9c8vysvvivx4bc1xa4gz7sl37y3i2k6-icecat-60.3.0-gnu1/lib/icecat/.icecat-real:3240): 
Pango-WARNING **: 10:16:13.114: font_face status is: file not 
found
(/gnu/store/x9c8vysvvivx4bc1xa4gz7sl37y3i2k6-icecat-60.3.0-gnu1/lib/icecat/.icecat-real:3240): 
Pango-WARNING **: 10:16:13.114: scaled_font status is: file not 
found
(/gnu/store/x9c8vysvvivx4bc1xa4gz7sl37y3i2k6-icecat-60.3.0-gnu1/lib/icecat/.icecat-real:3240): 
Gtk-WARNING **: 10:16:14.576: Could not load a pixbuf from 
/org/gtk/libgtk/theme/Adwaita/assets/check-symbolic.svg.
This may indicate that pixbuf loaders or the mime database could 
not be found.
```

Utilities from fontconfig (in the same profile) seem to work fine:

```
$ fc-match 'DejaVu Sans 9.9990234375'
DejaVuSans.ttf: "DejaVu Sans" "Book"
$ fc-list | grep DejaVuSans.ttf
~/.guix-profile/share/fonts/truetype/DejaVuSans.ttf
```

Any idea? How can I test if the issue is with pango or icecat or 
somewhere else? The "host" distro is Alpine.


Best,
---
Daniel Gerber