Fix const ilist_node::get{Prev,Next}Node() to actually compile. Picky, picky.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103723 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/unittests/ADT/ilistTest.cpp b/unittests/ADT/ilistTest.cpp
index 3bf04dc..09a699a 100644
--- a/unittests/ADT/ilistTest.cpp
+++ b/unittests/ADT/ilistTest.cpp
@@ -34,6 +34,11 @@
   EXPECT_EQ(2, List.back().Value);
   EXPECT_EQ(2, List.front().getNextNode()->Value);
   EXPECT_EQ(1, List.back().getPrevNode()->Value);
+
+  const ilist<Node> &ConstList = List;
+  EXPECT_EQ(2, ConstList.back().Value);
+  EXPECT_EQ(2, ConstList.front().getNextNode()->Value);
+  EXPECT_EQ(1, ConstList.back().getPrevNode()->Value);
 }
 
 }