[otlayout] Switch over from old is_a_ligature() to IS_LIGATED

Impact should be minimal and positive.
diff --git a/src/hb-ot-shape-complex-indic.cc b/src/hb-ot-shape-complex-indic.cc
index 0835f7d..1407ada 100644
--- a/src/hb-ot-shape-complex-indic.cc
+++ b/src/hb-ot-shape-complex-indic.cc
@@ -141,7 +141,7 @@
 is_one_of (const hb_glyph_info_t &info, unsigned int flags)
 {
   /* If it ligated, all bets are off. */
-  if (_hb_glyph_info_is_ligated (&info)) return false;
+  if (_hb_glyph_info_ligated (&info)) return false;
   return !!(FLAG (info.indic_category()) & flags);
 }
 
@@ -1406,7 +1406,7 @@
   if (start + 1 < end &&
       info[start].indic_position() == POS_RA_TO_BECOME_REPH &&
       ((info[start].indic_category() == OT_Repha) ^
-       _hb_glyph_info_is_ligated (&info[start])))
+       _hb_glyph_info_ligated (&info[start])))
   {
     unsigned int new_reph_pos;
     reph_position_t reph_pos = indic_plan->config->reph_pos;