[libcxx] Delete pointer in shared_ptr deduction test.

Updates the dummy deleter in deduction.pass.cpp to delete the pointer argument. This will fix the asan bots.

libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/deduction.pass.cpp

@@ -23,7 +23,10 @@
 struct A {};
 
 struct D {
-  void operator()(void*) const {}
+  void operator()(A* ptr) const
+  {
+    delete ptr;
+  }
 };
 
 int main(int, char**)