Temporarily added external annotations for ArrayList.clone() method and updated test data. Alternative signature annotations should be parsed for overridden methods, too.

compiler/testData/diagnostics/tests/alt-headers/ArrayListClone.jet

@@ -4,5 +4,5 @@ import java.util.*
 
 fun main(args : Array<String>) {
     val al : ArrayList<Int> = ArrayList<Int>()
-    al.clone() : Object // A type mismatch on this line means that alt-headers were not loaded
+    al.clone() : Any // A type mismatch on this line means that jdk-annotations were not loaded
 }

jdk-annotations/java/util/annotations.xml

@@ -734,4 +734,11 @@
       <val name="value" val="&quot;fun set(index : Int, element : E) : E&quot;"/>
     </annotation>
   </item>
+
+  <!-- TODO temporary fix for alt-headers/ArrayListClone.jet test -->
+  <item name='java.util.ArrayList java.lang.Object clone()'>
+    <annotation name='jet.runtime.typeinfo.KotlinSignature'>
+      <val name="value" val="&quot;fun clone() : Any&quot;"/>
+    </annotation>
+  </item>
 </root>