winex11: add alternative header

[Steven Edwards]

2009/9/19 André Hentschel <nerv at dawncrow.de>:
> Thanks for the hint, i had this construction from http://www.winehq.org/site/docs/winedev-guide/porting (which might be outdated)
> ill send a try 2

Yes I think the guide is wrong or at least misleading. If the #elif
case is there its not very common, at least in all the header patches
I've ever submitted for porting related issues. I've seen it used
plenty of times like the guide says for checking differing
implementation of functions and the like.

-- 
Steven Edwards

"There is one thing stronger than all the armies in the world, and
that is an idea whose time has come." - Victor Hugo