Add test for scala#1181 to pending

Author: odersky

tests/pending/pos/i1181.scala

@@ -0,0 +1,12 @@
+object Test {
+  def foo[M[_]](x: M[Int]) = x
+
+  type Alias[A] = (A, A)
+  val x: Alias[Int] = (1, 2)
+
+  foo[Alias](x) // ok
+  foo(x) // ok in scalac but fails in dotty with:
+         // error: type mismatch:
+         //  found   : (Int, Int)
+         //  required: M[Int]
+}