[aat] Fix mort shaping

Ouch!
diff --git a/src/hb-aat-layout.cc b/src/hb-aat-layout.cc
index da6908a..d9580c1 100644
--- a/src/hb-aat-layout.cc
+++ b/src/hb-aat-layout.cc
@@ -215,7 +215,7 @@
     return;
   }
 
-  hb_blob_t *mort_blob = font->face->table.morx.get_blob ();
+  hb_blob_t *mort_blob = font->face->table.mort.get_blob ();
   const AAT::mort& mort = *mort_blob->as<AAT::mort> ();
   if (mort.has_data ())
   {