LWG3828 Sync intmax_t and uintmax_t with C2x

Author: burblebee

source/iostreams.tex

@@ -18592,6 +18592,10 @@
 The header \libheader{cinttypes} includes the header \libheaderref{cstdint} instead
 of \libheader{stdint.h}, and
 \item
+\tcode{intmax_t} and \tcode{uintmax_t} are not required
+to be able to represent all values of extended integer types
+wider than \tcode{long long} and \tcode{unsigned long long} respectively, and
+\item
 if and only if the type \tcode{intmax_t} designates an extended integer
 type\iref{basic.fundamental}, the following function signatures are added:
 \begin{codeblock}