[woff2] Uncompress Brotli streams and `face_index' support.

WOFF2 compressed stream is now uncompressed if Brotli is available.
This data is stored in a separate buffer (uncompressed_buf) because
it does not contain direct table data.  Certain tables have
transformations applied to them, and they must be reconstructed
before we can write those tables to the SFNT stream.

`face_index' is now being passed as a parameter to
`woff2_open_font'.

* src/sfnt/sfobjs.c (sfnt_open_font): Add parameter
`face_instance_index'.

* src/sfnt/sfwoff2.c (woff2_uncompress): New function.
(woff2_open_font): Call `woff2_uncompress'.
(compute_first_table_offset): Fix return type.

* src/sfnt/sfwoff2.h (woff2_open_font): Modify declaration.
4 files changed