permissiveness in FreeType for CFF fonts

[Claudiu Milea]

Hi,

We encountered a few (potentially not fully compliant with the specification) 
CFF fonts (i.e. CIDFontType0) that have enough information to be rendered, but 
FreeType throws an exception due to not having both the `head` and the `cmap` 
tables.
I was wondering if the second `goto Exit;` in the following code could be 
changed to just logging a warning? With this change fonts that are missing the 
`head` table and don’t have a `cmap` could still be rendered.

In src/cff/cffobjs.c :

     /* now, the font can be either an OpenType/CFF font, or an SVG CEF */
      /* font; in the latter case it doesn't have a `head' table         */
      error = face->goto_table( face, TTAG_head, stream, 0 );
      if ( !error )
      {
        pure_cff = 0;

        /* load font directory */
        error = sfnt->load_face( stream, face, face_index,
                                 num_params, params );
        if ( error )
          goto Exit;
      }
      else
      {
       /* load the `cmap' table explicitly */
        error = sfnt->load_cmap( face, stream );
        if ( error )
          goto Exit;
      }

Thank you,
Andrei