Add in kernel irqchip save/restore support for pending vectors.

[avi: fix compile warning on i386]
[avi: remove printk]
Signed-off-by: Yaozu (Eddie) Dong <eddie.dong@intel.com>
Signed-off-by: Qing He <qing.he@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>