Mark cuchar tests as always xfail since we don't provide the header'

llvm-svn: 215873
diff --git a/libcxx/test/strings/c.strings/cuchar.pass.cpp b/libcxx/test/strings/c.strings/cuchar.pass.cpp
index d4c15db..022c656 100644
--- a/libcxx/test/strings/c.strings/cuchar.pass.cpp
+++ b/libcxx/test/strings/c.strings/cuchar.pass.cpp
@@ -7,7 +7,7 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// XFAIL: apple-darwin
+// XFAIL: *
 
 // <cuchar>