[ios.members.static] Add "static" to declaration

Author: tkoeppe

source/iostreams.tex

@@ -1325,7 +1325,7 @@
 
 \indexlibrarymember{sync_with_stdio}{ios_base}%
 \begin{itemdecl}
-bool sync_with_stdio(bool sync = true);
+static bool sync_with_stdio(bool sync = true);
 \end{itemdecl}
 
 \begin{itemdescr}