[libcxx] Remove uses of std::unique_ptr<T[N]> from test to prevent warning.

[EricWF]

Summary

constructing a std::unique_ptr<T[N]> will always cause a warning because the deleter (std::default_delete<T[N]>) will call delete ptr instead of delete [] ptr. This is a bug in the standard, not libc++.

I don't see a reason why removing the test cases will decrease coverage because std::unique_ptr<T> and std::unique_ptr<T[N]> select the same primary template. However since @mclow.lists wrote this test I want him to approve this patch.

[EricWF]

This was already committed.

test/std/utilities/tuple/tuple.general/tuple.smartptr.pass.cpp

     std::tuple<std::unique_ptr<char>> up;
     std::tuple<std::shared_ptr<char>> sp;
     std::tuple<std::weak_ptr  <char>> wp;
-//     std::tuple<std::auto_ptr  <char>> ap;
     }
     {
     std::tuple<std::unique_ptr<char[]>> up;
     std::tuple<std::shared_ptr<char[]>> sp;
     std::tuple<std::weak_ptr  <char[]>> wp;
-//     std::tuple<std::auto_ptr  <char[]>> ap;
     }
-    {
-    std::tuple<std::unique_ptr<char[5]>> up;
-    std::tuple<std::shared_ptr<char[5]>> sp;
-    std::tuple<std::weak_ptr  <char[5]>> wp;
-//     std::tuple<std::auto_ptr  <char[5]>> ap;
-    }
-}
+}