[varc] Reset component coordinates to that of the font

Fixes https://github.com/harfbuzz/boring-expansion-spec/issues/78

src/OT/glyf/Glyph.hh

@@ -370,7 +370,7 @@ struct Glyph
 
         comp_points.reset ();
 
-	coord_setter_t coord_setter (coords);
+	coord_setter_t coord_setter (hb_array (font->coords, font->num_coords));
 	item.set_variations (coord_setter, record_points);
 
 	if (unlikely (!glyf_accelerator.glyph_for_gid (item.get_gid ())