Linux has more than 32 address families defined in <bits/socket.h>. Use
a 64-bit type so all of them can be represented in the filter->families
bitmask.
It's easy to introduce bugs when using (1 << AF_FAMILY) because the
value is 32-bit. This can produce incorrect results from bitmask
operations so introduce the FAMILY_MASK() macro to eliminate these bugs.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>