[autofit] Code shuffling.

Also improve some comments and remove unused code.

No functional change.

* src/autofit/afloader.c (af_loader_load_g): Merged with...
(af_loader_load_glyph): ...this function.
Split off emboldening code into...
(af_loader_embolden_glyph_in_slot): ... this function.
2 files changed