[HarfBuzz] Minor patch

[Behdad Esfahbod]

While trying to see if the patch in this bug:

  http://bugzilla.gnome.org/show_bug.cgi?id=463430

is correct (it's not), I found a small bug in harfbuzz-gsub:

Index: harfbuzz-gsub.c
===================================================================
--- harfbuzz-gsub.c     (revision 2404)
+++ harfbuzz-gsub.c     (working copy)
@@ -4396,7 +4396,7 @@ static FT_Error  GSUB_Do_String_Lookup( 
       error = HB_Err_Not_Covered;
 
     if ( error == HB_Err_Not_Covered )
-      if ( hb_buffer_copy_output_glyph ( buffer ) )
+      if ( (error = hb_buffer_copy_output_glyph ( buffer ) ) )
        return error;
   }
 

Simon, can you please push to the relevant branches.

Cheers,
-- 
behdad
http://behdad.org/

"Those who would give up Essential Liberty to purchase a little
 Temporary Safety, deserve neither Liberty nor Safety."
        -- Benjamin Franklin, 1759