Rename uses of _ and __ because these are getting stepped on by macros from other system code.

llvm-svn: 167038
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 54d333a601a84e10710463e845f9f3a0cb6ca72b
diff --git a/include/iterator b/include/iterator
index 5747504..bcbf3ae 100644
--- a/include/iterator
+++ b/include/iterator
@@ -337,7 +337,7 @@
 struct __has_iterator_category
 {
 private:
-    struct __two {char _; char __;};
+    struct __two {char __lx; char __lxx;};
     template <class _Up> static __two __test(...);
     template <class _Up> static char __test(typename _Up::iterator_category* = 0);
 public: