[HarfBuzz] hb_fallback_shaper stuff

[John Emmas]

I just updated from Harfbuzz git master and tried to build with MSVC.  
When compiling src/hb-fallback-shape.cc it now gives me a lot of errors, 
starting with this at line 31:-

       error C2039: 'fallback' : is not a member of 'hb_shaper_data_t'

And there are other errors relating to 
'_hb_fallback_shaper_face_data_create' / 
'_hb_fallback_shaper_face_data_destroy' / 
'_hb_fallback_shaper_font_data_create' and 
'_hb_fallback_shaper_font_data_destroy' (all of them report "Identifier 
not found").  These ones seem to be due to the 
HB_SHAPER_DATA_ENSURE_DEFINE macros getting defined too early (if I move 
them so that they come after the relevant functions, those particular 
errors disappear).  However, I can't get rid of the errors which tell me 
that "fallback is not a member of 'hb_shaper_data_t".

Everything else still compiles okay AFAICT.

Any ideas..?

John