[meta.reflection.access.context] Use the usual "synopsis"-style codeblock for the class definition

Author: tkoeppe

source/meta.tex

@@ -4197,21 +4197,23 @@
 \pnum
 An \tcode{access_context} has an associated scope and designating class.
 
-\begin{itemdecl}
-struct access_context {
-  access_context() = delete;
+\indexlibraryglobal{access_context}%
+\begin{codeblock}
+namespace std::meta {
+  struct access_context {
+    access_context() = delete;
 
-  consteval info scope() const;
-  consteval info designating_class() const;
+    consteval info scope() const;
+    consteval info designating_class() const;
 
-  static consteval access_context current() noexcept;
-  static consteval access_context unprivileged() noexcept;
-  static consteval access_context unchecked() noexcept;
-  consteval access_context via(info cls) const;
-};
-\end{itemdecl}
+    static consteval access_context current() noexcept;
+    static consteval access_context unprivileged() noexcept;
+    static consteval access_context unchecked() noexcept;
+    consteval access_context via(info cls) const;
+  };
+}
+\end{codeblock}
 
-\begin{itemdescr}
 \pnum
 \tcode{access_context} is a structural type.
 Two values \tcode{ac1} and \tcode{ac2} of type \tcode{access_context}
@@ -4220,7 +4222,6 @@
 are template-argument-equivalent
 and \tcode{ac1.desig\-nating_class()} and \tcode{ac2.desig\-nating_class()}
 are template-argument-equivalent.
-\end{itemdescr}
 
 \begin{itemdecl}
 consteval info @\libmember{scope}{access_context}@() const;