mm/sl[aou]b: Common alignment code

Extract the code to do object alignment from the allocators.
Do the alignment calculations in slab_common so that the
__kmem_cache_create functions of the allocators do not have
to deal with alignment.

Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

diff --cc mm/slab.c
Simple merge

diff --cc mm/slab.h
Simple merge

diff --cc mm/slab_common.c
Simple merge

diff --cc mm/slob.c
Simple merge

diff --cc mm/slub.c
Simple merge