Without the chnage the build fails as https://hydra.nixos.org/build/317973907
on `master as:
gcc -c -o src/bdf.o src/bdf.c
src/bdf.c:131:1: error: conflicting types for 'glyph_open'; have 'bdf_glyph_t *(int, int)' {aka 'struct _bdf_glyph_t *(int, int)'}
131 | glyph_open(int width, int height)
| ^~~~~~~~~~
