Generally speaking, this question in this form just doesn't come up much in Europe as, "who is white" is much less of a discussion point than in the US, along with all "race" discussions. This is not to say that racism or xenophobia don't exist in Europe, but animosity exists inbetween "whites" as well, and people can hate Arabs without thinking about it in terms of "whites" vs Arabs, and rather thinking about it as "my nation" vs "strangers". Not saying this is much better, just trying to point out that not all parts of the world are obsessed with the American flavor of the concept of race. For one, it's definitely never ever used officially as a concept in many European countries.