[PATCH] sysctl: make sure that /proc/sys/net/ipv4 appears before per-ns ones

Massage ipv4 initialization - make sure that net.ipv4 appears as
non-per-net-namespace before it shows up in per-net-namespace sysctls.
That's the only change outside of sysctl.c needed to get sane ordering
rules and data structures for sysctls (esp. for procfs side of that
mess).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>