lib/test_meminit: add a kmem_cache_alloc_bulk() test

lib/test_meminit: add a kmem_cache_alloc_bulk() test

Make sure allocations from kmem_cache_alloc_bulk() and
kmem_cache_free_bulk() are properly initialized.

Link: http://lkml.kernel.org/r/20191007091605.30530-2-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Thibaut Sautereau <thibaut@sautereau.fr>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>