[input.output] Add references to inclusions in a synopsis

Author: tkoeppe

source/iostreams.tex

@@ -367,10 +367,10 @@
 \indexlibrary{\idxhdr{iostream}}%
 
 \begin{codeblock}
-#include <ios>
-#include <streambuf>
-#include <istream>
-#include <ostream>
+#include <ios>          // see \ref{ios.syn}
+#include <streambuf>    // see \ref{streambuf.syn}
+#include <istream>      // see \ref{istream.syn}
+#include <ostream>      // see \ref{ostream.syn}
 
 namespace std {
   extern istream cin;
@@ -629,7 +629,7 @@
 \indexlibrary{\idxcode{io_errc}}%
 
 \begin{codeblock}
-#include <iosfwd>
+#include <iosfwd>   // see \ref{iosfwd.syn}
 
 namespace std {
   using streamoff  = @\impdef@;
@@ -4038,9 +4038,9 @@
 
 \rSec1[iostream.format]{Formatting and manipulators}
 
+\rSec2[istream.syn]{Header \tcode{<istream>} synopsis}
 \indextext{\idxhdr{istream}}%
 \indexlibrary{\idxhdr{istream}}%
-\rSec2[istream.syn]{Header \tcode{<istream>} synopsis}
 
 \begin{codeblock}
 namespace std {
@@ -14779,7 +14779,6 @@
 \rSec1[c.files]{C library files}
 
 \rSec2[cstdio.syn]{Header \tcode{<cstdio>} synopsis}
-
 \indextext{\idxhdr{cstdio}}%
 \indextext{\idxhdr{cstdio}}%
 \indexlibrary{\idxcode{size_t}}%
@@ -14846,6 +14845,7 @@
 \indexlibrary{\idxcode{feof}}%
 \indexlibrary{\idxcode{ferror}}%
 \indexlibrary{\idxcode{perror}}%
+
 \begin{codeblock}
 namespace std {
   using size_t = @\textit{see \ref{support.types.layout}}@;
@@ -15003,7 +15003,7 @@
 \indexlibrary{\idxcode{SCNuPTR}}%
 \indexlibrary{\idxcode{SCNxPTR}}%
 \begin{codeblock}
-#include <cstdint>
+#include <cstdint>  // see \ref{cstdint.syn}
 
 namespace std {
   using imaxdiv_t = @\seebelow@;