[autofit] Use unsigned accounting for hints.

* src/autofit/afhints.h (AF_AxisHintsRec): Use unsigned types.

* src/autofit/afhints.c (af_axis_hints_new_{segment,edge},
af_glyph_hints_get_num_segments, af_glyph_hints_get_segment_offset):
Updated accordingly.
* src/autofit/aflatin.c (af_cjk_hints_compute_edges): Ditto.
* src/autofit/afcjk.c (af_cjk_hints_compute_edges): Ditto.
4 files changed