[util.smartptr.shared.create] Fix macro application

Author: tkoeppe

source/utilities.tex

@@ -9761,9 +9761,9 @@
 \indexlibrary{\idxcode{allocate_shared}}%
 \begin{itemdecl}
 template<class T, ...>
-  shared_ptr<T> make_shared(\placeholder{args});
+  shared_ptr<T> make_shared(@\placeholdernc{args}@);
 template<class T, class A, ...>
-  shared_ptr<T> allocate_shared(const A& a, \placeholder{args});
+  shared_ptr<T> allocate_shared(const A& a, @\placeholdernc{args}@);
 \end{itemdecl}
 
 \begin{itemdescr}