slab: fix DEBUG_SLAB build

Fix CONFIG_SLAB=y CONFIG_DEBUG_SLAB=y build error and warnings.

Now that ARCH_SLAB_MINALIGN defaults to __alignof__(unsigned long long),
it is always defined (when slab.h included), but cannot be used in #if:
mm/slab.c: In function `cache_alloc_debugcheck_after':
mm/slab.c:3156:5: warning: "__alignof__" is not defined
mm/slab.c:3156:5: error: missing binary operator before token "("
make[1]: *** [mm/slab.o] Error 1

So just remove the #if and #endif lines, but then 64-bit build warns:
mm/slab.c: In function `cache_alloc_debugcheck_after':
mm/slab.c:3156:6: warning: cast from pointer to integer of different size
mm/slab.c:3158:10: warning: format `%d' expects type `int', but argument
                            3 has type `long unsigned int'
Fix those with casts, whatever the actual type of ARCH_SLAB_MINALIGN.
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

mm/slab.c

@@ -3153,12 +3153,10 @@ static void *cache_alloc_debugcheck_after(struct kmem_cache *cachep,
 	objp += obj_offset(cachep);
 	if (cachep->ctor && cachep->flags & SLAB_POISON)
 		cachep->ctor(objp);
-#if ARCH_SLAB_MINALIGN
-	if ((u32)objp & (ARCH_SLAB_MINALIGN-1)) {
+	if ((unsigned long)objp & (ARCH_SLAB_MINALIGN-1)) {
 		printk(KERN_ERR "0x%p: not aligned to ARCH_SLAB_MINALIGN=%d\n",
-		       objp, ARCH_SLAB_MINALIGN);
+		       objp, (int)ARCH_SLAB_MINALIGN);
 	}
-#endif
 	return objp;
 }
 #else