fix x86_64 build break

x86_64 can not build on @1.1746 42badf41asjaKoYentyODb8CdFEydg

===== xen/include/public/arch-x86_64.h 1.42 vs edited =====

@@ -187,6 +187,8 @@
     unsigned long gdt_frames[16], gdt_ents; /* GDT (machine frames, # 

ents) */
unsigned long kernel_ss, kernel_sp; /* Virtual TSS (only
SS1/SP1) */
unsigned long pt_base; /* CR3 (pagetable base)
*/
+ unsigned long cr0; /* CR0

     */

+ unsigned long cr4; /* CR4
*/
unsigned long debugreg[8]; /* DB0-DB7 (debug
registers) */

     unsigned long event_callback_eip;
     unsigned long failsafe_callback_eip;

sorry I had the fix in my repository but forgot to push it. it's fix now.

thanks,

Vincent Hanquez