[libcxx] [test] Fix unused local typedef warnings.

llvm-svn: 314259

libcxx/test/std/strings/basic.string/string.ops/string_find.last.not.of/string_view_size.pass.cpp

@@ -150,8 +150,8 @@ int main()
     }
 #if TEST_STD_VER >= 11
     {
-    typedef std::basic_string<char, std::char_traits<char>, min_allocator<char>> S;
-    typedef std::string_view SV;
+//     typedef std::basic_string<char, std::char_traits<char>, min_allocator<char>> S;
+//     typedef std::string_view SV;
 //     test0<S, SV>();
 //     test1<S, SV>();
     }