Otherwise we get a ton of unaligned exceptions, for cases such
as compat_sys_msgrcv() which go:
p = compat_alloc_user_space(second + sizeof(struct msgbuf));
and here 'second' can for example be an arbitrary odd value.
Based upon a bug report from Jurij Smakov.
Signed-off-by: David S. Miller <davem@davemloft.net>
