This avoids additional calls to `tt_face_lookup_table' for the
`glyf' table, which can be expensive.
* include/freetype/internal/tttypes.h (TT_LoaderRec): Move
`glyf_offset' field to ...
(TT_FaceRec): ... this structure.
* src/truetype/ttgload.c (load_truetype_glyph): Updated.
(tt_loader_init): Move initialization of `glyf_offset' to ...
* src/truetype/ttpload.c (tt_face_load_loca): .. this function.