[Xcb] xcb_aux.h patch for use with C++

[Barton C Massey]

Thanks for the patch!  Pushed.

It would be really helpful if you could start using git with
us at some point.  Let me know if you need some help getting
started.

	Bart

In message <200809292155.31836.doomster at knuut.de> you wrote:
> The patch addresses a few things which are needed for use with C++:
> 
> - Use 'class_' instead of 'class' as parameter name. At the same time, I 
> replaced '_class' with 'class_', because anything beginning with an 
> underscore might be a reserved global. This is just to be rather safe than 
> sorry.
> 
> - Rewrite XCB_AUX_ADD_PARAM to not rely on void-pointer arithmetic, which 
> simply isn't allowed in C++. Further, I renamed _XCB_AUX_OFFSETOF to 
> XCB_AUX_INTERNAL_OFFSETOF, because macros beginning with a leading underscore 
> followed by a capital are also reserved to the compiler implementor. I also 
> tried to document what the macros do and how (I hope I guessed right).
> 
> cheers
> 
> Uli