[C2y] Claim nonconformance to WG14 N3418

This paper makes it a constraint violation to form a UCN via token
concatenation. Clang does not conform to it and the paper goes in the
opposite direction of where C++ went with P2621R3 which was adopted for
C++26.

Author: AaronBallman

clang/www/c_status.html

@@ -304,7 +304,7 @@ <h2 id="c2y">C2y implementation status</h2>
     <tr>
       <td>Slay Some Earthly Demons XIV</td>
       <td><a href="https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3418.pdf">N3418</a></td>
-      <td class="unknown" align="center">Unknown</td>
+      <td class="none" align="center">No</td>
 	</tr>
     <tr>
       <td>Slay Some Earthly Demons XVI</td>