opengl32: make the old code before the "sync the dibsection to its pixmap" patch be selectable at runtime

[Lionel Ulmer]

> What says that a gl context can be used by one thread only? In the 
> glxDestroyContext man page it sounds like a context has a sort of reference 
> count, and it can be used by multiple threads.

man glXMakeCurrent

       BadAccess  is  generated  if  ctx  was  current to another
       thread at the time glXMakeCurrent was called.
	      
Seems pretty clear to me, but well, my man pages may be outdated :-)

          Lionel

-- 
		 Lionel Ulmer - http://www.bbrox.org/