lockdep: require framepointers for x86

Require framepointers for x86, because otherwise we'll be having
empty stack traces, which is useless.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1236167295.5330.7240.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>