can't use meson for 'freetype-demos'

[Werner LEMBERG]

[274212df5a7812430010e9cc67cbb2a4f5203288, gsoc-2022-chariri]

Hello Charlie,


I've just tried

```
meson setup meson-build
```

and I got

  src/ftinspect/meson.build:49:2:
    ERROR: File widgets/glyphcontinuous.hpp does not exist.

Please fix.


     Werner