[myanmar] Don’t disable liga feature

This seems to have been carried over from the Indic shaper, but
Uniscribe enables it by default.

See https://github.com/harfbuzz/harfbuzz/issues/2213#issuecomment-686062915
diff --git a/src/hb-ot-shape-complex-myanmar.cc b/src/hb-ot-shape-complex-myanmar.cc
index fc3490d..294ab34 100644
--- a/src/hb-ot-shape-complex-myanmar.cc
+++ b/src/hb-ot-shape-complex-myanmar.cc
@@ -97,12 +97,6 @@
     map->enable_feature (myanmar_other_features[i], F_MANUAL_ZWJ);
 }
 
-static void
-override_features_myanmar (hb_ot_shape_planner_t *plan)
-{
-  plan->map.disable_feature (HB_TAG('l','i','g','a'));
-}
-
 
 enum myanmar_syllable_type_t {
   myanmar_consonant_syllable,
@@ -346,7 +340,7 @@
 const hb_ot_complex_shaper_t _hb_ot_complex_shaper_myanmar =
 {
   collect_features_myanmar,
-  override_features_myanmar,
+  nullptr, /* override_features */
   nullptr, /* data_create */
   nullptr, /* data_destroy */
   nullptr, /* preprocess_text */