Use shared_ptr<hb_set_t> in one place

See if valgrind is happy...

src/hb-map.hh

diff --git a/src/hb-map.hh b/src/hb-map.hh
index 065ae17..d3bb49a 100644
--- a/src/hb-map.hh
+++ b/src/hb-map.hh
@@ -198,7 +198,7 @@
     return true;
   }
 
-  bool set (K key, const V& value) { return set_with_hash (key, hb_hash (key), value); }
+  bool set (K key, const V &value) { return set_with_hash (key, hb_hash (key), value); }
   bool set (K key, V&& value) { return set_with_hash (key, hb_hash (key), std::move (value)); }
 
   V get (K key) const

src/hb-ot-layout-gsubgpos.hh

diff --git a/src/hb-ot-layout-gsubgpos.hh b/src/hb-ot-layout-gsubgpos.hh
index fff5974..0482785 100644
--- a/src/hb-ot-layout-gsubgpos.hh
+++ b/src/hb-ot-layout-gsubgpos.hh
@@ -111,12 +111,9 @@
 
       if (!done_lookups_glyph_set->get (lookup_index))
       {
-	hb_set_t* empty_set = hb_set_create ();
+	hb::shared_ptr<hb_set_t> empty_set {hb_set_create ()};
 	if (unlikely (!done_lookups_glyph_set->set (lookup_index, empty_set)))
-	{
-	  hb_set_destroy (empty_set);
 	  return true;
-	}
       }
 
       hb_set_clear (done_lookups_glyph_set->get (lookup_index));
@@ -171,7 +168,7 @@
   hb_closure_context_t (hb_face_t *face_,
 			hb_set_t *glyphs_,
 			hb_map_t *done_lookups_glyph_count_,
-			hb_hashmap_t<unsigned, hb_set_t *> *done_lookups_glyph_set_,
+			hb_hashmap_t<unsigned, hb::shared_ptr<hb_set_t>> *done_lookups_glyph_set_,
 			unsigned int nesting_level_left_ = HB_MAX_NESTING_LEVEL) :
 			  face (face_),
 			  glyphs (glyphs_),
@@ -195,7 +192,7 @@
 
   private:
   hb_map_t *done_lookups_glyph_count;
-  hb_hashmap_t<unsigned, hb_set_t *> *done_lookups_glyph_set;
+  hb_hashmap_t<unsigned, hb::shared_ptr<hb_set_t>> *done_lookups_glyph_set;
   unsigned int lookup_count = 0;
 };
 

src/hb-ot-layout.cc

diff --git a/src/hb-ot-layout.cc b/src/hb-ot-layout.cc
index 9a8070a..f5031be 100644
--- a/src/hb-ot-layout.cc
+++ b/src/hb-ot-layout.cc
@@ -1501,15 +1501,12 @@
 					hb_set_t     *glyphs /* OUT */)
 {
   hb_map_t done_lookups_glyph_count;
-  hb_hashmap_t<unsigned, hb_set_t *> done_lookups_glyph_set;
+  hb_hashmap_t<unsigned, hb::shared_ptr<hb_set_t>> done_lookups_glyph_set;
   OT::hb_closure_context_t c (face, glyphs, &done_lookups_glyph_count, &done_lookups_glyph_set);
 
   const OT::SubstLookup& l = face->table.GSUB->table->get_lookup (lookup_index);
 
   l.closure (&c, lookup_index);
-
-  for (auto _ : done_lookups_glyph_set.iter ())
-    hb_set_destroy (_.second);
 }
 
 /**
@@ -1529,7 +1526,7 @@
 					 hb_set_t       *glyphs /* OUT */)
 {
   hb_map_t done_lookups_glyph_count;
-  hb_hashmap_t<unsigned, hb_set_t *> done_lookups_glyph_set;
+  hb_hashmap_t<unsigned, hb::shared_ptr<hb_set_t>> done_lookups_glyph_set;
   OT::hb_closure_context_t c (face, glyphs, &done_lookups_glyph_count, &done_lookups_glyph_set);
   const GSUB& gsub = *face->table.GSUB->table;
 
@@ -1551,9 +1548,6 @@
     }
   } while (iteration_count++ <= HB_CLOSURE_MAX_STAGES &&
 	   glyphs_length != glyphs->get_population ());
-
-  for (auto _ : done_lookups_glyph_set.iter ())
-    hb_set_destroy (_.second);
 }
 
 /*