lib/test_meminit.c: add bulk alloc/free tests

lib/test_meminit.c: add bulk alloc/free tests

kmem_cache_alloc_bulk/kmem_cache_free_bulk are used to make multiple
allocations of the same size to avoid the overhead of multiple
kmalloc/kfree calls.  Extend the kmem_cache tests to make some calls to
these APIs.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Laura Abbott <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Tested-by: Alexander Potapenko <[email protected]>
Cc: Laura Abbott <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Nick Desaulniers <[email protected]>
Cc: Kostya Serebryany <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Sandeep Patil <[email protected]>
Cc: Jann Horn <[email protected]>
Cc: Marco Elver <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>