[ft] FT_Open_Face with negative face_index

[David Osborn]

The FreeType2 docs mention that, if the face_index parameter of 
FT_Open_Face is negative, '* face', which I'm assuming refers to the 
function's 'aface' parameter, will not be filled in.  See: 
http://freetype.sourceforge.net/freetype2/docs/reference/ft2-base_interface.html#FT_Open_Face 
(look under the 'note' heading).  This suggests that I should be able to 
pass a null pointer as the aface parameter since its not going to be 
used anyway.  However, the function fails if I do that, so my assumption 
must be wrong.  If I pass it a real pointer to an FT_Face instance, it 
fills it in even though the face_index is negative (the docs say it 
'will not return any face handle' in this case).  FT_Open_Face seems to 
operate as if the face_index were 0 even if I pass -1.  The only 
possibility I can think of is if I'm misinterpreting what '* face' means 
in the docs.  Any suggestions?