[sfnt] Consolidate POST version 2.0 and 2.5 (pt 1).

The deprecated POST version 2.5 can be handled using the data
structures of version 2.0.  The goal is to reduce the footprint.

* include/freetype/internal/tttypes.h (TT_Post_Names): Absorb and...
(TT_Post_20, TT_Post_25): ... remove these structures.
src/sfnt/ttpost.c (load_post_names, tt_face_get_ps_name,
tt_face_free_ps_names, load_format_20): Updated accordingly.
(load_format_25): ditto and convert offsets to glyph indices.
2 files changed