[aat] Implement Lookup table

Untested, but compiles.
diff --git a/src/hb-ot-cmap-table.hh b/src/hb-ot-cmap-table.hh
index 883d7b3..c61801c 100644
--- a/src/hb-ot-cmap-table.hh
+++ b/src/hb-ot-cmap-table.hh
@@ -508,7 +508,7 @@
   {
     inline void init (hb_face_t *face)
     {
-      this->blob = OT::Sanitizer<OT::cmap>::sanitize (face->reference_table (HB_OT_TAG_cmap));
+      this->blob = OT::Sanitizer<OT::cmap>().sanitize (face->reference_table (HB_OT_TAG_cmap));
       const OT::cmap *cmap = OT::Sanitizer<OT::cmap>::lock_instance (this->blob);
       const OT::CmapSubtable *subtable = nullptr;
       const OT::CmapSubtableFormat14 *subtable_uvs = nullptr;