[class.union.anon] Tighten definition of "variant member"

[hubert-reinterpretcast]

Rephrase the definition of variant members to address the following problems with the current wording:

• It creates a misleading reading of the "[in] addition, [ ... ]" sentence as applying only to the case where X is a union.
• It is not phrased as complete/exhaustive.

[eisenwave]

Suggested change

	The \defnx{variant members}{variant member} of a union-like class \tcode{X} are the variant
	members of the anonymous union members of \tcode{X} and, if \tcode{X} is a union, the
	non-static data members of \tcode{X} other than anonymous union members.
	The \defnx{variant members}{variant member} of a union-like class \tcode{X} are
	the variant members of the anonymous union members of \tcode{X}, and
	if \tcode{X} is a union, the non-static data members of \tcode{X} other than anonymous union members.

If we're touching this section anyway, it seems beneficial to reflow the text so that if it was turned into bullets, we'd only need to add \items at the start of each line.

The \defnx{variant members}{variant member} of a union-like class \tcode{X} are
\begin{itemize}
\item the variant members of the anonymous union members of \tcode{X}, and
\item if \tcode{X} is a union, the non-static data members of \tcode{X} other than anonymous union members.
\end{itemize}

[eisenwave]

Personally, I don't think this paragraph is that broken though. The suggestion seems like a slight upgrade.

[hubert-reinterpretcast]

The placement of the comma in the suggestion is less grammatical as the list is of two items and the commas are parenthetical (around the condition introduced with the "if") in nature.