[PATCH] x86_64: small fix for CFI annotations

Conditionalize two unwind directives to match other similarly
conditional code.

Signed-Off-By: Jan Beulich <jbeulich@novell.com>
Cc: Jim Houston <jim.houston@ccur.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>