[basic.fundamental,cstdarg.syn] Use full reference for ISO C sections

Fixes ISO/CS comment (C++23)

Author: jensmaurer

source/basic.tex

@@ -5072,11 +5072,11 @@
 alternative representations of the value specified by the value representation.
 \begin{note}
 Padding bits have unspecified value, but cannot cause traps.
-In contrast, see ISO C 6.2.6.2.
+In contrast, see \IsoC{} 6.2.6.2.
 \end{note}
 \begin{note}
 The signed and unsigned integer types satisfy
-the constraints given in ISO C 5.2.4.2.1.
+the constraints given in \IsoC{} 5.2.4.2.1.
 \end{note}
 Except as specified above,
 the width of a signed or unsigned integer type is

source/support.tex

@@ -5802,7 +5802,7 @@
 standard library header \libheader{stdarg.h}, with the following changes:
 \begin{itemize}
 \item
-In lieu of the default argument promotions specified in ISO C 6.5.2.2,
+In lieu of the default argument promotions specified in \IsoC{} 6.5.2.2,
 the definition in~\ref{expr.call} applies.
 \item
 The restrictions that ISO C places on the second parameter to the