ancillary data alignment will be ALIGNBYTES, not sizeof(long) - 1, from now.
CMSG_xx will NOT resolve into constant. if you use CMSG_xx to allocate
arrays, you'll lose.
bump shlib minor for libc.
NOTE: if you are on top of arch with ALIGNBYTES != sizeof(long) - 1,
you need to recompile IPv6-related binaries. there is no way to guarantee
backward compat in this aspect. sorry for this. this should be the last
backward compat breakage for IPv6-related ancillary data manipulation.
(we still have PR 9516 for unix-domain sockets...)