lockdep: add stack dumps to asserts

Have a better idea about exactly which loc causes a lockdep
limit overflow. Often it's a bug or inefficiency in that
subsystem.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1237376327.5069.253.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>