[PATCH] x86_64: Reduce screen space needed by stack trace

Especially under Xen, where the console cannot be adjusted to more than 25
lines, it is fairly important that the information displayed during a panic
is as compact as possible. Below adjustments work towards that.

Signed-Off-By: Jan Beulich <jbeulich@novell.com>

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>