RFC: remove sn2, hpsim and ia64 machvecs v2

[Christoph Hellwig]

[adding some ex-SGI folks to comment as well]

Hi Tony,

let me know what you think of this series.  This drops the pretty much
dead sn2 and hpsim support, which then allows us to build a single ia64
kernel image that supports all remaining systems without extra indirections
in the fast path.

A git tree is also available at:

    git://git.infradead.org/users/hch/misc.git ia64-remove-machvecs

Gitweb:

    http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/ia64-remove-machvecs

Changes since v1:
 - restore !NUMA support
 - fix compile for configs