APIC: record local APIC state on boot

Xen does not store the boot local APIC state which leads to problems
when shutting down for a kexec jump.  This patch records the boot
state so we can return to the boot state when kexecing.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

diff -r cac82bc1ea23 xen/arch/x86/apic.c
--- a/xen/arch/x86/apic.c	Wed Jun 15 13:33:58 2011 +0100
+++ b/xen/arch/x86/apic.c	Wed Jun 15 14:36:02 2011 +0100
@@ -78,7 +78,7 @@ boolean_param("x2apic", opt_x2apic);
  * Bootstrap processor local APIC boot mode - so we can undo our changes
  * to the APIC state.
  */
-static enum apic_mode apic_boot_mode = APIC_MODE_INVALID;
+enum apic_mode apic_boot_mode = APIC_MODE_INVALID;
 
 bool_t __read_mostly x2apic_enabled = 0;
 bool_t __read_mostly directed_eoi_enabled = 0;