[libcxx] [test] Replace _LIBCPP_STD_VER with TEST_STD_VER.

This replaces every occurrence of _LIBCPP_STD_VER in the tests with
TEST_STD_VER. Additionally, for every affected
file, #include "test_macros.h" is being added explicitly if it wasn't
already there.

https://reviews.llvm.org/D26294

llvm-svn: 286007

libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.pointer.pass.cpp

@@ -17,6 +17,7 @@
 #include <string_view>
 #include <cassert>
 
+#include "test_macros.h"
 #include "constexpr_char_traits.hpp"
 
 template <class S>
@@ -49,7 +50,7 @@ int main()
     test("abcdefghijklmnopqrst", S("abcdefghijklmnopqrst"), true, true);
     }
 
-#if _LIBCPP_STD_VER > 11
+#if TEST_STD_VER > 11
     {
     typedef std::basic_string_view<char, constexpr_char_traits<char>> SV;
     constexpr SV  sv1;