[aat] Expose a couple APIs

New API:
+hb_aat_layout_has_substitution()
+hb_aat_layout_has_positioning()

docs/harfbuzz-sections.txt

@@ -12,6 +12,8 @@ hb_aat_layout_feature_type_get_name_id
 hb_aat_layout_feature_selector_t
 hb_aat_layout_feature_selector_info_t
 hb_aat_layout_feature_type_get_selector_infos
+hb_aat_layout_has_substitution
+hb_aat_layout_has_positioning
 </SECTION>
 
 <SECTION>

src/hb-aat-layout.cc

@@ -205,7 +205,14 @@ hb_aat_layout_compile_map (const hb_aat_map_builder_t *mapper,
 }
 
 
-bool
+/*
+ * hb_aat_layout_has_substitution:
+ * @face:
+ *
+ * Returns:
+ * Since: REPLACEME
+ */
+hb_bool_t
 hb_aat_layout_has_substitution (hb_face_t *face)
 {
   return face->table.morx->has_data () ||
@@ -259,9 +266,14 @@ hb_aat_layout_remove_deleted_glyphs (hb_buffer_t *buffer)
   hb_ot_layout_delete_glyphs_inplace (buffer, is_deleted_glyph);
 }
 
-
-
-bool
+/*
+ * hb_aat_layout_has_positioning:
+ * @face:
+ *
+ * Returns:
+ * Since: REPLACEME
+ */
+hb_bool_t
 hb_aat_layout_has_positioning (hb_face_t *face)
 {
   return face->table.kerx->has_data ();

src/hb-aat-layout.h

@@ -457,6 +457,22 @@ hb_aat_layout_feature_type_get_selector_infos (hb_face_t
 					       unsigned int                          *default_index   /* OUT.     May be NULL. */);
 
 
+/*
+ * morx/mort
+ */
+
+HB_EXTERN hb_bool_t
+hb_aat_layout_has_substitution (hb_face_t *face);
+
+
+/*
+ * kerx
+ */
+
+HB_EXTERN hb_bool_t
+hb_aat_layout_has_positioning (hb_face_t *face);
+
+
 HB_END_DECLS
 
 #endif /* HB_AAT_LAYOUT_H */

src/hb-aat-layout.hh

@@ -56,9 +56,6 @@ HB_INTERNAL void
 hb_aat_layout_compile_map (const hb_aat_map_builder_t *mapper,
 			   hb_aat_map_t *map);
 
-HB_INTERNAL bool
-hb_aat_layout_has_substitution (hb_face_t *face);
-
 HB_INTERNAL void
 hb_aat_layout_substitute (const hb_ot_shape_plan_t *plan,
 			  hb_font_t *font,
@@ -70,9 +67,6 @@ hb_aat_layout_zero_width_deleted_glyphs (hb_buffer_t *buffer);
 HB_INTERNAL void
 hb_aat_layout_remove_deleted_glyphs (hb_buffer_t *buffer);
 
-HB_INTERNAL bool
-hb_aat_layout_has_positioning (hb_face_t *face);
-
 HB_INTERNAL void
 hb_aat_layout_position (const hb_ot_shape_plan_t *plan,
 			hb_font_t *font,