[otlayout] Add _hb_glyph_info_set_glyph_props()

No functional change.
diff --git a/src/hb-ot-layout-private.hh b/src/hb-ot-layout-private.hh
index 406a042..9468b34 100644
--- a/src/hb-ot-layout-private.hh
+++ b/src/hb-ot-layout-private.hh
@@ -321,6 +321,15 @@
   return lig_id;
 }
 
+/* glyph_props: */
+
+inline void
+_hb_glyph_info_set_glyph_props (hb_glyph_info_t *info, unsigned int props)
+{
+  info->glyph_props() = props;
+}
+
+
 
 
 #endif /* HB_OT_LAYOUT_PRIVATE_HH */