[NETFILTER] x_tables: Make XT_ALIGN align as strictly as necessary.

Or else we break on ppc32 and other 32-bit platforms.

Based upon a patch from Harald Welte.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/netfilter/x_tables.h

@@ -19,7 +19,7 @@ struct xt_get_revision
 /* For standard target */
 #define XT_RETURN (-NF_REPEAT - 1)
 
-#define XT_ALIGN(s) (((s) + (__alignof__(void *)-1)) & ~(__alignof__(void *)-1))
+#define XT_ALIGN(s) (((s) + (__alignof__(u_int64_t)-1)) & ~(__alignof__(u_int64_t)-1))
 
 /* Standard return verdict, or do jump. */
 #define XT_STANDARD_TARGET ""