Update Mackerras-3-Clause-acknowledgment.xml

I reverted to the first fix commit.

src/Mackerras-3-Clause-acknowledgment.xml

@@ -34,7 +34,7 @@
                <bullet>3.</bullet>
                Redistributions of any form whatsoever must retain the
                following acknowledgment: "This product includes software
-               developed by Paul Mackerras &lt;<alt match="([email protected]|[email protected])" name="emailAddress">[email protected]</alt>&gt;".
+               developed by Paul Mackerras <alt match="(&lt;[email protected]&gt;|&lt;[email protected]&gt;)" name="emailAddress">&lt;[email protected]&gt;</alt>".
             </item>
          </list>
          <p>