[truetype] Updates for the forthcoming OpenType 1.9 standard (1/2).

This is in preparation for implementing `DeltaSetIndexMap` format 1, which
is used by `COLR` v1 tables, and which allows 32bit indices.

  https://docs.microsoft.com/en-us/typography/opentype/otspec190/delta/otvarcommonformats_delta.html

* src/truetype/ttgxvar.h (GX_DeltaSetIdxMapRec): Change type of `mapCount`
to `FT_ULong`.

* src/truetype/ttgxvar.c (ft_var_load_delta_set_index_mapping): Add argument
for passing the table size; update caller.
Implement new format.
2 files changed