Make abstract-report2 test less dependent on std library.

Replace the use of `Ordering` by custom, dummy trait Xyz defined in test's
source.

By not inheriting from Ordering in abstract-report2 we make the test
less dependent on both Scala and Java library. The reason we are less
dependent on Java is because Ordering extends Java's comparator.

This change is motivated by the fact that Java 8 introduced default
method `reversed` to Comparator interface and we get a failure due to
conflicting inheritance:

-abstract-report2.scala:9: error: trait Bippy inherits conflicting members:
-  method reversed in trait TraversableOnce of type => List[(T2, String)]  and
-  method reversed in trait Comparator of type ()java.util.Comparator[T3]
-(Note: this can be resolved by declaring an override in trait Bippy.)
-trait Bippy[T1, T2, T3] extends Collection[T1] with TraversableOnce[(T2, String)] with Ordering[T3]
-      ^

1 files changed, 4 insertions, 4 deletions

diff --git a/test/files/neg/abstract-report2.check b/test/files/neg/abstract-report2.check
index 6ea949353a..9be3d822f2 100644
--- a/test/files/neg/abstract-report2.check
+++ b/test/files/neg/abstract-report2.check
@@ -61,7 +61,7 @@ it has 13 unimplemented members.
 
 class Baz[T] extends Collection[T]
       ^
-abstract-report2.scala:11: error: class Dingus needs to be abstract, since:
+abstract-report2.scala:15: error: class Dingus needs to be abstract, since:
 it has 24 unimplemented members.
 /** As seen from class Dingus, the missing signatures are as follows.
  *  For convenience, these are usable as stub implementations.
@@ -84,9 +84,6 @@ it has 24 unimplemented members.
   def toIterator: Iterator[(Set[Int], String)] = ???
   def toStream: Stream[(Set[Int], String)] = ???
 
-  // Members declared in scala.math.Ordering
-  def compare(x: List[Int],y: List[Int]): Int = ???
-
   // Members declared in scala.collection.TraversableOnce
   def copyToArray[B >: (Set[Int], String)](xs: Array[B],start: Int,len: Int): Unit = ???
   def exists(p: ((Set[Int], String)) => Boolean): Boolean = ???
@@ -98,6 +95,9 @@ it has 24 unimplemented members.
   def seq: scala.collection.TraversableOnce[(Set[Int], String)] = ???
   def toTraversable: Traversable[(Set[Int], String)] = ???
 
+  // Members declared in Xyz
+  def foo(x: List[Int]): Boolean = ???
+
 class Dingus extends Bippy[String, Set[Int], List[Int]]
       ^
 four errors found