Set correct value of `face->num_faces' for WOFF2 fonts. This is
being handled separately because we only load the tables for the
requested font face in `woff2_open_font' and create a single-face
sfnt stream.
The full discussion is at:
https://lists.gnu.org/archive/html/freetype-devel/2019-08/msg00000.html
* src/sfnt/sfobjs.c (sfnt_open_font): Add parameter
`woff2_num_faces'.
(sfnt_init_face): Introduce variable `woff2_num_faces', and change
`face->root.num_faces' if `woff2_num_faces' is set.
* src/sfnt/sfwoff2.c (woff2_open_font): Validate requested face
index and handle negative face indices.
* src/sfnt/sfwoff2.h (woff2_open_font): Add parameter `num_faces' to
declaration.
5367e0ca01