[stmt.while] Format the while rewrite rule the same way we format

rewrite rules for other statement forms.

Author: zygoloid

source/statements.tex

@@ -514,16 +514,16 @@
 is an initialized declaration of some variable \tcode{t}
 is equivalent to
 
-\begin{codeblock}
-label:
-{                   // start of condition scope
-  @\grammarterm{condition}@ ;      @\,@// declares \tcode{t}
-  if (t) {
-    @\grammarterm{statement}@
-    goto label;
-  }
-}                   // end of condition scope
-\end{codeblock}
+\begin{ncbnftab}
+\terminal{label:}\br
+\terminal{\{}\>\>\>// start of condition scope\br
+\>condition \terminal{;}\>\>// declares \terminal{t}\br
+\>\terminal{if (t) \{}\br
+\>\>statement\br
+\>\>\terminal{goto label;}\br
+\>\terminal{\}}\br
+\terminal{\}}\>\>\>// end of condition scope
+\end{ncbnftab}
 
 \begin{note}
 The variable created in the condition is destroyed and created with each