[facet.num.put.virtuals] Move long code fragment to codeblock

Author: tkoeppe

source/locales.tex

@@ -2984,9 +2984,10 @@
 
 \stage{2}
 Any character \tcode{c} other than a decimal point(.) is converted to a
-\tcode{charT}
-via
-\tcode{use_facet<ctype<charT>>(loc).widen( c )}
+\tcode{charT} via
+\begin{codeblock}
+use_facet<ctype<charT>>(loc).widen(c)
+\end{codeblock}
 
 A local variable \tcode{punct} is initialized via
 \begin{codeblock}