[nomerge] Reuse tasksupport in CombinerFactory

Reported in scala-parallel-collections 152.

Author: lrytz

library/src/scala/collection/parallel/ParIterableLike.scala

@@ -574,7 +574,11 @@ self: ParIterableLike[T, Repr, Sequential] =>
       def apply() = shared
       def doesShareCombiners = true
     } else new CombinerFactory[T, Repr] {
-      def apply() = newCombiner
+      def apply() = {
+        val r = newCombiner
+        r.combinerTaskSupport = tasksupport
+        r
+      }
       def doesShareCombiners = false
     }
   }
@@ -587,7 +591,11 @@ self: ParIterableLike[T, Repr, Sequential] =>
       def apply() = shared
       def doesShareCombiners = true
     } else new CombinerFactory[S, That] {
-      def apply() = cbf()
+      def apply() = {
+        val r = cbf()
+        r.combinerTaskSupport = tasksupport
+        r
+      }
       def doesShareCombiners = false
     }
   }