[PATCH] x86_64: Make kernel math errors a die() now

There were no reports about the previous warning for FPU exceptions in the
kernel, so make it a die() now.

Also improve the error messages slightly.

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