fixup: remove BNF to be deleted

Author: jensmaurer

source/classes.tex

@@ -4867,12 +4867,6 @@
 A friend declaration that does not declare a function
 shall be a \grammarterm{friend-type-declaration}.
 
-\begin{ncsimplebnf}
-\keyword{friend} elaborated-type-specifier \terminal{;}\br
-\keyword{friend} simple-type-specifier \terminal{;}\br
-\keyword{friend} typename-specifier \terminal{;}
-\end{ncsimplebnf}
-
 \begin{note}
 A friend declaration can be the
 \grammarterm{declaration} in