[PATCH] [libcxx] Cleanup and fix is_destructible and tests in C++03.

[Eric Fiselier]

>>! In D6316#4, @mclow.lists wrote:
> I'm unsure why we're testing for `__has_feature(cxx_noexcept)` in is_nothrow_destructible.pass.cpp

The toggle between the C++11 and C++03 implementation of  `is_nothrow_destructible` is `__has_feature(cxx_noexcept)`.  I think it is silly, but that is the way it currently works.

================
Comment at: test/utilities/meta/meta.unary/meta.unary.prop/is_nothrow_destructible.pass.cpp:72
@@ -70,2 +71,3 @@
     test_is_not_nothrow_destructible<char[]>();
+    test_is_not_nothrow_destructible<char[][3]>();
 
----------------
mclow.lists wrote:
> I like the idea of adding a test for an array of known bound, but did you mean `[3]` or `[][3]` ??
There is a test for an array of a known bound below. I just wanted to make sure a multi-dimensional array with an unknown bound was handled as I expected.

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Comment at: test/utilities/meta/meta.unary/meta.unary.prop/is_trivially_destructible.pass.cpp:40
@@ -39,2 +39,3 @@
 {
+public:
     virtual ~NotEmpty();
----------------
I think this change sneaked in. Is this dtor meant to be private?

http://reviews.llvm.org/D6316