[cassert.syn] Better index the macro in this header

source/diagnostics.tex

@@ -456,9 +456,8 @@
 
 \rSec2[cassert.syn]{Header \tcode{<cassert>} synopsis}
 
-\indexlibraryglobal{assert}%
 \begin{codeblock}
-#define assert(...) @\seebelow@
+#define @\libmacro{assert}@(...) @\seebelow@
 \end{codeblock}
 
 \rSec2[assertions.assert]{The \tcode{assert} macro}
@@ -468,11 +467,11 @@
 at the point in the source file where \tcode{<cassert>} is included,
 the \tcode{assert} macro is defined as
 \begin{codeblock}
-#define assert(...) ((void)0)
+#define @\libmacro{assert}@(...) ((void)0)
 \end{codeblock}
 
 \pnum
-Otherwise, the \tcode{assert} macro puts a diagnostic test into programs;
+Otherwise, the \libmacro{assert} macro puts a diagnostic test into programs;
 it expands to an expression of type \keyword{void} which
 has the following effects: