include: Create todo_wine_if.

[Sebastian Lackner]

On 22.01.2016 17:50, Bernhard Übelacker wrote:
> +#define todo_if(is_todo, platform) for (winetest_start_todo_if(is_todo, platform); \
> +                                        winetest_loop_todo(); \
> +                                        winetest_end_todo_if(is_todo, platform))

There is a high risk of corrupting todo_level if is_todo changes in the meantime.
Nevertheless, I like the general idea of introducing such a command, it would make
some tests much easier and avoid duplicated checks.