Replace __cplusplus comparisons and dialect __has_feature checks with TEST_STD_VER.

This is a huge cleanup that helps make the libc++ test suite more portable.
Patch from STL@microsoft.com. Thanks STL!


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@272716 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/containers/associative/multimap/multimap.cons/move.pass.cpp

@@ -75,7 +75,7 @@ int main()
         assert(mo.size() == 0);
         assert(distance(mo.begin(), mo.end()) == 0);
     }
-#if __cplusplus >= 201103L
+#if TEST_STD_VER >= 11
     {
         typedef test_compare<std::less<int> > C;
         typedef min_allocator<V> A;