xen migration patches for stable/longterm

[Stefan Bader]

Currently there is a problem with unmasking event channels on resume
which causes panics on migration. This was fixed in 2.6.37, so it
affects .32, .33, and .35 longterm (not sure about .27).

This is fixed by:

Author: Ian Campbell <ian.campbell at citrix.com>
Date:   Mon Nov 1 16:30:09 2010 +0000

    xen: events: do not unmask event channels on resume
    
    commit 6903591f314b8947d0e362bda7715e90eb9df75e upstream

Talking with Ian, he felt that this change was rather hackish and
using two more cleanup patches would feel more appropriate. As those
where going upstream in 2.6.39 they would be applicable for any
stable/longterm at least back to 2.6.32.y. Though slight modifications
are required for some older releases.

Author: Thomas Gleixner <tglx at linutronix.de>
Date:   Fri Feb 4 13:19:20 2011 +0100

    genirq: Add IRQF_FORCE_RESUME
    
    commit dc5f219e88294b93009eef946251251ffffb6d60 upstream
    (backport required for .32 and .33)

Author: Thomas Gleixner <tglx at linutronix.de>
Date:   Sat Feb 5 20:08:59 2011 +0000

    xen: Use IRQF_FORCE_RESUME
    
    commit 676dc3cf5bc36a9e129a3ad8fe3bd7b2ebf20f5d upstream
    (backport required for .32, .33, .35)

Both seem to be cleanups and reporters would indicate success with
only the first patch applied, so I would leave the decission about
the other two patches up to the stable maintainers.

I am posting the patches as required by .32 as follow-ups to this
mail. Whenever a backport is required by other releases, the .32
version would apply.

-Stefan