[build] Generation of the javadoc was broken

We've split up the build dirs for various phases of the lombok compile process,
and evidently `javadoc` doesn't work unless it can find all types involved on the classpath,
even for types that only show up internally. I was thinking javadoc should just look at
(protected/public) signatures, not internals, but, alas.

buildScripts/website.ant.xml

@@ -218,6 +218,7 @@ such as applying the templates to produce the website, converting the changelog
 			<package name="lombok.experimental" />
 			<package name="lombok.extern.*" />
 			<classpath location="build/lombok-main" />
+			<classpath location="build/lombok-utils" />
 			<header><![CDATA[<a href='https://projectlombok.org/' target='_blank'>Lombok</a> - ]]>v${lombok.version}</header>
 			<bottom><![CDATA[<i>Copyright &copy; 2009-${javadoc.year} The Project Lombok Authors, licensed under the <a href='http://www.opensource.org/licenses/mit-license.php' target='_blank'>MIT licence</a>.]]></bottom>
 		</javadoc>