Misc drive-by cleanups. NFC

http://reviews.llvm.org/D12294


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@245876 91177308-0d34-0410-b5e6-96231b3b80d8

test/libcxx/atomics/libcpp-has-no-threads.fail.cpp

@@ -0,0 +1,23 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <atomic>
+
+// Test that including <atomic> fails to compile when _LIBCPP_HAS_NO_THREADS
+// is defined.
+
+#ifndef _LIBCPP_HAS_NO_THREADS
+#define _LIBCPP_HAS_NO_THREADS
+#endif
+
+#include <atomic>
+
+int main()
+{
+}

test/libcxx/atomics/libcpp-has-no-threads.pass.cpp

@@ -0,0 +1,18 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+// XFAIL: libcpp-has-no-threads
+
+#ifdef _LIBCPP_HAS_NO_THREADS
+#error This should be XFAIL'd for the purpose of detecting that the LIT feature\
+   'libcpp-has-no-threads' is available iff _LIBCPP_HAS_NO_THREADS is defined
+#endif
+
+int main()
+{
+}