selftests/move_mount_set_group:Make tests build with old libc

Replace SYS_<syscall> with __NR_<syscall>. Using the __NR_<syscall>
notation, provided by UAPI, is useful to build tests on systems without
the SYS_<syscall> definitions.

Replace SYS_move_mount with __NR_move_mount

Similar changes: commit 87129ef13603 ("selftests/landlock: Make tests build with old libc")

Acked-by: Mickaël Salaün <[e-mail]>
Signed-off-by: Hu.Yadi <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Berlin <[e-mail]>
Suggested-by: Jiao <[e-mail]>
Signed-off-by: Christian Brauner <[e-mail]>

tools/testing/selftests/move_mount_set_group/move_mount_set_group_test.c

···
 	if (mount(NULL, SET_GROUP_FROM, NULL, MS_SHARED, 0))
 		return -1;
 
-	ret = syscall(SYS_move_mount, AT_FDCWD, SET_GROUP_FROM,
+	ret = syscall(__NR_move_mount, AT_FDCWD, SET_GROUP_FROM,
 		      AT_FDCWD, SET_GROUP_TO, MOVE_MOUNT_SET_GROUP);
 	umount2("/tmp", MNT_DETACH);
 
···
 		       CLONE_VM | CLONE_FILES); ASSERT_GT(pid, 0);
 	ASSERT_EQ(wait_for_pid(pid), 0);
 
-	ASSERT_EQ(syscall(SYS_move_mount, ca_from.mntfd, "",
+	ASSERT_EQ(syscall(__NR_move_mount, ca_from.mntfd, "",
 			  ca_to.mntfd, "", MOVE_MOUNT_SET_GROUP
 			  | MOVE_MOUNT_F_EMPTY_PATH | MOVE_MOUNT_T_EMPTY_PATH),
 		  0);