[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

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@286007 91177308-0d34-0410-b5e6-96231b3b80d8
252 files changed