[range.concat.view] Mark make-unsigned-like-t with \exposid (#6933)

Author: hewillk

source/ranges.tex

@@ -8707,7 +8707,7 @@
 \begin{codeblock}
 return apply(
   [](auto... sizes) {
-    using CT = make-unsigned-like-t<common_type_t<decltype(sizes)...>>;
+    using CT = @\exposid{make-unsigned-like-t}@<common_type_t<decltype(sizes)...>>;
     return (CT(sizes) + ...);
   },
   tuple-transform(ranges::size, @\exposid{views_}@));