Cleanup non-standard tests as reported by STL@microsoft.com. NFC.

This patch addresses the following issues in the test suite:

1. Move "std::bad_array_length" test from std/ to libcxx/ test directory
   since the feature is not a part of the standard.

2. Rename "futures.tas" test directory to "futures.task" since that is the
   correct stable name.

3. Move tests for "packaged_task<T>::result_type" from std/ to libcxx/
   test directory since the typedef is a libc++ extension.


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@271430 91177308-0d34-0410-b5e6-96231b3b80d8

include/future

@@ -322,7 +322,7 @@ template <class R, class... ArgTypes>
 class packaged_task<R(ArgTypes...)>
 {
 public:
-    typedef R result_type;
+    typedef R result_type; // extension
 
     // construction and destruction
     packaged_task() noexcept;
@@ -1998,7 +1998,7 @@ template<class _Rp, class ..._ArgTypes>
 class _LIBCPP_TYPE_VIS_ONLY packaged_task<_Rp(_ArgTypes...)>
 {
 public:
-    typedef _Rp result_type;
+    typedef _Rp result_type; // extension
 
 private:
     __packaged_task_function<result_type(_ArgTypes...)> __f_;
@@ -2127,7 +2127,7 @@ template<class ..._ArgTypes>
 class _LIBCPP_TYPE_VIS_ONLY packaged_task<void(_ArgTypes...)>
 {
 public:
-    typedef void result_type;
+    typedef void result_type; // extension
 
 private:
     __packaged_task_function<result_type(_ArgTypes...)> __f_;

test/libcxx/thread/futures/futures.task/types.pass.cpp

@@ -16,7 +16,9 @@
 //     class packaged_task<R(ArgTypes...)>
 // {
 // public:
-//     typedef R result_type;
+//     typedef R result_type; // extension
+
+// This is a libc++ extension.
 
 #include <future>
 #include <type_traits>