Address some post-commit review comments on r217261

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@217276 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/ios b/include/ios
index 6d42607..ff79998 100644
--- a/include/ios
+++ b/include/ios
@@ -216,7 +216,7 @@
 #include <__locale>
 #include <system_error>
 
-#if __has_feature(cxx_atomic) && !_LIBCPP_HAS_NO_THREADS
+#if __has_feature(cxx_atomic) && !defined(_LIBCPP_HAS_NO_THREADS)
 #include <atomic>     // for __xindex_
 #endif
 
@@ -367,7 +367,7 @@
     int*            __index_;
     size_t          __event_size_;
     size_t          __event_cap_;
-#if __has_feature(cxx_atomic) && !_LIBCPP_HAS_NO_THREADS
+#if __has_feature(cxx_atomic) && !defined(_LIBCPP_HAS_NO_THREADS)
     static atomic<int> __xindex_;
 #else
     static int      __xindex_;