[PATCH] x86-64: Use X86_EFLAGS_IF in x86-64/irqflags.h.

As per i386 patch: move X86_EFLAGS_IF et al out to a new header:
processor-flags.h, so we can include it from irqflags.h and use it in
raw_irqs_disabled_flags().

As a side-effect, we could now use these flags in .S files.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andi Kleen <ak@suse.de>