Added test case for varargs bridges

Currently we cannot run this test automatically because the testing framework
does not know about .java files. It was run manually and verified that ElimRepeated
does was it is supposed to do (create a varargs bridge).

Author: odersky

tests/disabled/java-interop/pos/varargs-bridge/A.java

@@ -0,0 +1,8 @@
+package test;
+public class A {
+
+    int foo(int... x) {
+        return x.length;
+    }
+
+}

tests/disabled/java-interop/pos/varargs-bridge/B.scala

@@ -0,0 +1,7 @@
+package test
+class B extends A {
+  override def foo(x: Int*): Int = x.length + 1
+}
+object B extends App {
+  println(new B().foo(1, 2, 3))
+}