Quiet two more large allocation warnings

Both of these allocations are larger than 8k which trips the
warning, but so no large that they must be vmem_alloc()'ed.  For
this case I have added the KM_NODEBUG flag which silences the
warning.  The flag also acts as a marker in the source so I can
keep track of this as something which needs to be better addressed
in the long term.

SPL: large kmem_alloc(11876, 0x50) at get_nvlist:911 (341009/1877530)
SPL: large kmem_alloc(11240, 0x50) at load_nvlist:1273 (2639492/2643588)

Closes #50

module/zfs/spa.c

@@ -1265,7 +1265,7 @@ load_nvlist(spa_t *spa, uint64_t obj, nvlist_t **value)
 	nvsize = *(uint64_t *)db->db_data;
 	dmu_buf_rele(db, FTAG);
 
-	packed = kmem_alloc(nvsize, KM_SLEEP);
+	packed = kmem_alloc(nvsize, KM_SLEEP | KM_NODEBUG);
 	error = dmu_read(spa->spa_meta_objset, obj, 0, nvsize, packed,
 	    DMU_READ_PREFETCH);
 	if (error == 0)

module/zfs/zfs_ioctl.c

@@ -893,7 +893,7 @@ get_nvlist(uint64_t nvl, uint64_t size, int iflag, nvlist_t **nvp)
 	if (size == 0)
 		return (EINVAL);
 
-	packed = kmem_alloc(size, KM_SLEEP);
+	packed = kmem_alloc(size, KM_SLEEP | KM_NODEBUG);
 
 	if ((error = ddi_copyin((void *)(uintptr_t)nvl, packed, size,
 	    iflag)) != 0) {