Grow: fix resize of array component size to > 32bits

If the request --size to --grow an array to is larger
than 32bits, then mdadm may make the wrong choice and
use ioctl instead of setting component_size via sysfs
and the change is ignored.

Instead of using casts to check for a 32-bit overflow,
just check for set bits outside of INT32_MAX.

Fixes: 4e9a3dd16d
Signed-off-by: NeilBrown <neilb@suse.de>

Grow.c

@@ -1818,7 +1818,7 @@ int Grow_reshape(char *devname, int fd,
 		if (s->size == MAX_SIZE)
 			s->size = 0;
 		array.size = s->size;
-		if (array.size != (signed)s->size) {
+		if (s->size & ~INT32_MAX) {
 			/* got truncated to 32bit, write to
 			 * component_size instead
 			 */