[PATCH] Intel Sandy Bridge support for hwpmc

Good evening folks.
During last days I've written a patch to add sandy bridge support to
hwpmc. Until now, the most recent Intel processor microarchitecture
supported was Westmere.
Testing is appreciated, in order to see if there's something that have
to be fixed.
You can find the diff here: http://davit.altervista.rg/hwpmc_sandy_bridge.diff

I'd like to thanks a lot attilio_at_ that helped me to fix a bug and gnn_at_
and fabient_at_ for the useful suggestions.

Best

Davide