x86: kdump failure

kdump needs ELF_CORE_COPY_REGS in crash_save_cpu().
This lack of the macro causes the following BUG.

 SysRq : Trigger a crashdump
 ------------[ cut here ]------------
 kernel BUG at include/linux/elfcore.h:105!
 invalid opcode: 0000 [1] PREEMPT SMP

Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>