alpha: fix SOCK_DIAG_BY_FAMILY tests

This complements commit v4.9-368-g301c65c.

* tests/netlink_inet_diag.c (check_responses): Align "buf"
on sizeof(long) boundary.
* tests/netlink_unix_diag.c (check_responses): Likewise.
diff --git a/tests/netlink_unix_diag.c b/tests/netlink_unix_diag.c
index 5d760a2..0879bf0 100644
--- a/tests/netlink_unix_diag.c
+++ b/tests/netlink_unix_diag.c
@@ -83,7 +83,7 @@
 static void
 check_responses(const int fd)
 {
-	static char buf[8192];
+	static long buf[8192 / sizeof(long)];
 	struct sockaddr_nl nladdr = {
 		.nl_family = AF_NETLINK
 	};