Add tests to ensure that string/vector/array have contiguous iterators - which they did. Mark N4284 as complete

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@238233 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/containers/sequences/array/contiguous.pass.cpp

@@ -0,0 +1,31 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// <array>
+
+// An array is a contiguous container
+
+#include <array>
+#include <cassert>
+
+template <class C>
+void test_contiguous ( const C &c )
+{
+    for ( size_t i = 0; i < c.size(); ++i )
+        assert ( *(c.begin() + i) == *(std::addressof(*c.begin()) + i));
+}
+
+int main()
+{
+    {
+        typedef double T;
+        typedef std::array<T, 3> C;
+        test_contiguous (C());
+    }
+}