We finally got the OK from all contributors with non-trivial commits to
relicense systemd from GPL2+ to LGPL2.1+.
Some udev bits continue to be GPL2+ for now, but we are looking into
relicensing them too, to allow free copy/paste of all code within
systemd.
The bits that used to be MIT continue to be MIT.
The big benefit of the relicensing is that closed source code may now
link against libsystemd-login.so and friends.
This patch introduces socket_ipv6_is_supported() call that checks for
IPv6 availability. Code then check for it before using specific calls.
In order to be less intrusive, this patch avoids IPv6 entries being
parsed at all, this way we don't get such entries in the system and
all other code paths are automatically ignored. However an extra check
is done at socket_address_listen() to make sure of that.
As the number of Netlink messages is not know upfront anymore,
loopback-setup.c was refactored to dynamically calculate the sequence
number and count.
Lennart's suggestions were fixed and squashed with the original patch,
that was sent by Gustavo Sverzut Barbieri (barbieri@profusion.mobi).
