Fixup hb_ot_shape_closure()

Broke it when merged cmap mapping and normalizer.  Ouch!
diff --git a/src/hb-ot-shape.cc b/src/hb-ot-shape.cc
index 3f72fd0..313766a 100644
--- a/src/hb-ot-shape.cc
+++ b/src/hb-ot-shape.cc
@@ -589,7 +589,7 @@
 {
   unsigned int count = buffer->len;
   for (unsigned int i = 0; i < count; i++)
-    font->get_glyph (buffer->cur().codepoint, 0, &buffer->cur().codepoint);
+    font->get_glyph (buffer->info[i].codepoint, 0, &buffer->info[i].codepoint);
 }
 
 void