Fixup: Use \idxcode for index entries

Author: jensmaurer

source/utilities.tex

@@ -12939,8 +12939,8 @@
 \rSec2[functional.syn]{Header \tcode{<functional>} synopsis}
 
 \indexhdr{functional}%
-\indexlibrary{unwrap_ref_decay}%
-\indexlibrary{unwrap_ref_decay_t}%
+\indexlibrary{\idxcode{unwrap_ref_decay}}%
+\indexlibrary{\idxcode{unwrap_ref_decay_t}}%
 \begin{codeblock}
 namespace std {
   // \ref{func.invoke}, invoke
@@ -13373,7 +13373,7 @@
 
 \rSec3[refwrap.unwrapref]{Transformation type trait \tcode{unwrap_reference}}
 
-\indexlibrary{unwrap_reference}%
+\indexlibrary{\idxcode{unwrap_reference}}%
 \begin{itemdecl}
 template<class T>
   struct unwrap_reference;