[range.utility.conv.to] Add terminating condition for first bullet

We currently fail to say what happens if the first bullet is true, but
then none of its sub-bullets is true.

Author: jwakely

source/ranges.tex

@@ -2336,6 +2336,8 @@
   c.reserve(static_cast<range_size_t<C>>(ranges::size(r)));
 ranges::copy(r, @\exposid{container-inserter}@<range_reference_t<R>>(c));
 \end{codeblock}
+\item
+Otherwise, the program is ill-formed.
 \end{itemize}
 
 \item