Add test for by-name varargs

Author: odersky

tests/pos/byNameVarargs.scala

@@ -0,0 +1,15 @@
+package test
+
+object O {
+
+  def byname(xs: => Int*) = xs.sum
+  def byval(xs: Int*) = xs.sum
+
+  def a = 1
+  def b = 2
+
+  byval(a, b)
+  byname(a, b)
+
+}
+