local_t: Remove leftover local.h

Somehow the local.h was not removed when taking out the local_t usage during
the 2.6.32 merge.

CC: David Miller <davem@davemloft.net>
Signed-off-by: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Tejun Heo <tj@kernel.org>