[otlayout] Add HB_OT_LAYOUT_GLYPH_PROPS_LIGATED

Currently unused.

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

@@ -616,13 +616,18 @@ struct hb_apply_context_t
   }
 
   inline void _set_glyph_props (hb_codepoint_t glyph_index,
-			  unsigned int class_guess = 0) const
-  {
-    unsigned int add_in = HB_OT_LAYOUT_GLYPH_PROPS_SUBSTITUTED;
+			  unsigned int class_guess = 0,
+			  bool ligature = false) const
+  {
+    unsigned int add_in = _hb_glyph_info_get_glyph_props (&buffer->cur()) &
+			  HB_OT_LAYOUT_GLYPH_PROPS_PRESERVE;
+    add_in |= HB_OT_LAYOUT_GLYPH_PROPS_SUBSTITUTED;
+    if (ligature)
+      add_in |= HB_OT_LAYOUT_GLYPH_PROPS_LIGATED;
     if (likely (has_glyph_classes))
       _hb_glyph_info_set_glyph_props (&buffer->cur(), add_in | gdef.get_glyph_props (glyph_index));
     else if (class_guess)
-      _hb_glyph_info_set_glyph_props (&buffer->cur(), add_in| class_guess);
+      _hb_glyph_info_set_glyph_props (&buffer->cur(), add_in | class_guess);
   }
 
   inline void replace_glyph (hb_codepoint_t glyph_index) const
@@ -638,7 +643,7 @@ struct hb_apply_context_t
   inline void replace_glyph_with_ligature (hb_codepoint_t glyph_index,
 					   unsigned int class_guess) const
   {
-    _set_glyph_props (glyph_index, class_guess);
+    _set_glyph_props (glyph_index, class_guess, true);
     buffer->replace_glyph (glyph_index);
   }
   inline void output_glyph (hb_codepoint_t glyph_index,

src/hb-ot-layout-private.hh

@@ -50,8 +50,11 @@ typedef enum
   HB_OT_LAYOUT_GLYPH_PROPS_MARK		= 0x08u,
 
   /* The following are used internally; not derived from GDEF. */
-  HB_OT_LAYOUT_GLYPH_PROPS_SUBSTITUTED	= 0x10u
+  HB_OT_LAYOUT_GLYPH_PROPS_SUBSTITUTED	= 0x10u,
+  HB_OT_LAYOUT_GLYPH_PROPS_LIGATED	= 0x20u,
 
+  HB_OT_LAYOUT_GLYPH_PROPS_PRESERVE     = HB_OT_LAYOUT_GLYPH_PROPS_SUBSTITUTED |
+					  HB_OT_LAYOUT_GLYPH_PROPS_LIGATED
 } hb_ot_layout_glyph_class_mask_t;