Fix mistake in `quote` optimiser
Found by Pip Cet. * lisp/emacs-lisp/byte-opt.el (byte-optimize-quote): Fix mistake that made this optimiser ineffective at removing quoting of nil, t, and keywords. The only obvious consequence is that we no longer need... (byte-optimize-form): ...a 'nil => nil normalising step here; remove. (byte-optimize-form-code-walker): Make the compiler warn about (quote).