wrapping (some) ipis in arch/x86/

[Cherry G . Mathew]

ftp://ftp.netbsd.org/pub/NetBSD/misc/cherry/tmp/wrap_ipi.diff

Hi,

I'd like to ask peoples' opinions about the above patch. This would
remove a couple of #ifdef XEN/#endif pairs I had to introduce
lately. 

Cheers,
-- 
Cherry