Revert "[libc++] Fix PR35491 - std::array of zero-size doesn't work with non-default constructible types."

Revert "Fix initialization of array<const T, 0> with GCC."
Revert "Make array<const T, 0> non-CopyAssignable and make swap and fill ill-formed."

This reverts commit r324182, r324185, and r324194 which were causing issues with zero-length std::arrays.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@324309 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/containers/sequences/array/array.cons/default.pass.cpp

@@ -14,14 +14,6 @@
 #include <array>
 #include <cassert>
 
-// std::array is explicitly allowed to be initialized with A a = { init-list };.
-// Disable the missing braces warning for this reason.
-#include "disable_missing_braces_warning.h"
-
-struct NoDefault {
-  NoDefault(int) {}
-};
-
 int main()
 {
     {
@@ -36,13 +28,4 @@ int main()
         C c;
         assert(c.size() == 0);
     }
-    {
-      typedef std::array<NoDefault, 0> C;
-      C c;
-      assert(c.size() == 0);
-      C c1 = {};
-      assert(c1.size() == 0);
-      C c2 = {{}};
-      assert(c2.size() == 0);
-    }
 }