Add the papers that were applied to the latest C2x working draft

Author: AaronBallman

clang/www/c_status.html

@@ -816,6 +816,32 @@ <h2 id="c2x">C2x implementation status</h2>
       <td><a href="http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2607.pdf">N2607</a></td>
       <td class="partial" align="center">Partial</td>
     </tr>
+    <!-- Apr 2021 Papers -->
+    <tr>
+      <td>String functions for freestanding implementations</td>
+      <td><a href="http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2524.htm">N2524</a></td>
+      <td class="none" align="center">No</td>
+    </tr>
+    <tr>
+      <td>Digit separators</td>
+      <td><a href="http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2626.pdf">N2626</a></td>
+      <td class="full" align="center">Clang 13</td>
+    </tr>
+    <tr>
+      <td>Missing DEC_EVAL_METHOD</td>
+      <td><a href="http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2640.htm">N2640</a></td>
+      <td class="unknown" align="center">Unknown</td>
+    </tr>
+    <tr>
+      <td>Missing +(x) in table</td>
+      <td><a href="http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2641.htm">N2641</a></td>
+      <td class="unknown" align="center">Unknown</td>
+    </tr>
+    <tr>
+      <td>Add support for preprocessing directives elifdef and elifndef</td>
+      <td><a href="http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2645.pdf">N2645</a></td>
+      <td class="full" align="center">Clang 13</td>
+    </tr>
 </table>
 </details>