[Xcb] Using C99 types instead of custom integral types

[Vincent Torri]

> On Wed, 6 Sep 2006, Josh Triplett wrote:
>
>> This does raise the question of whether we might want to use these types
>> in our protocol headers rather than the typedefs.
>
> I say it's about time to enter the nineties ;)

Not everyone has a computer / compiler from the nineties ;) (I know such 
people)

Vincent