[IA64] Support domU coredump on ia64

[IA64] Support domU coredump on ia64

This patch supports domU coredump on ia64.  xen_panic_event() is
registered to panic_notifier_list, and xen_panic_event() calls
HYPERVISOR_shutdown(SHUTDOWN_crash) at panic time.

If xend is notified of crash status, xend calls dumpCore()
and create domU's core in /var/xen/dump.

For sample crash module and usage, see:

http://lists.xensource.com/archives/html/xen-ia64-devel/2006-07/msg00230.html

Signed-off-by: Akio Takebe <takebe_akio@jp.fujitsu.com>
[minor code re-arrangement]
Signed-off-by: Alex Williamson <alex.williamson@hp.com>