Towards using top-byte of unicode-props for more things

src/hb-ot-layout-gsubgpos-private.hh

@@ -835,7 +835,6 @@ static inline bool ligate_input (hb_apply_context_t *c,
     _hb_glyph_info_set_lig_props_for_ligature (&buffer->cur(), lig_id, total_component_count);
     if (_hb_glyph_info_get_general_category (&buffer->cur()) == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)
     {
-      _hb_glyph_info_set_modified_combining_class (&buffer->cur(), 0);
       _hb_glyph_info_set_general_category (&buffer->cur(), HB_UNICODE_GENERAL_CATEGORY_OTHER_LETTER);
     }
   }

src/hb-ot-layout-private.hh

@@ -258,7 +258,8 @@ static inline void
 _hb_glyph_info_set_general_category (hb_glyph_info_t *info,
 				     hb_unicode_general_category_t gen_cat)
 {
-  info->unicode_props() = (unsigned int) gen_cat | (info->unicode_props() & ~UPROPS_MASK_GEN_CAT);
+  /* Clears top-byte. */
+  info->unicode_props() = (unsigned int) gen_cat | (info->unicode_props() & (0xFF & ~UPROPS_MASK_GEN_CAT));
 }
 
 static inline hb_unicode_general_category_t