networkd: add back path of MTU discovery for SIT
networkd: add Patch of MTU discovery for IPIP and GRE

Add path of MTU disovery for IPIP and GRE Kind of tunnels
sd-rtnl: fix reading of nla type

We must filter out the 'network-byteorder' and 'nested' flags.
sd-rtnl: mark nested attributes with the NLA_F_NESTED flag

The kernel mostly does not check this, but let's be consisntent and allways set it anyway. Based
on patch from Susant Sahani.
sd-rtnl: add support to set packet family type

This patch adds functionality to set family type
in the rtnl message for example PF_BRIDGE.
sd-rtnl: add bridge port rtnl attributes.

Add bridge port attributes to sd-rtnl to configure
via networkd.
util: make use of the new getrandom() syscall if it is available when needing entropy

Doesn't require an fd, and could be a bit faster, so let's make use of
it, if it is available.
missing: simplify memfd ifdeffery
update TODO
missing: no tabs please, we are british
sd-bus: properly handle removals of non-existing matches
nspawn: ignore EEXIST when creating mount point

A combination of commits f3c80515c and 79d80fc14 cause nspawn to
silently fail with a commandline such as:

  # systemd-nspawn -D /build/extra-x86_64 --bind=/usr

strace shows the culprit:

  [pid 27868] writev(2, [{"Failed to create mount point /build/extra-x86_64/usr: File exists", 82}, {"\n", 1}], 2) = 83
busctl: add new "capture" verb to record bus messages in libpcap compatible files, for dissection with wireshark
udev: path_id - update comments
missing.h: fix wrong __NR_getrandom syscall def

278 is vmsplice on x86_64. 318 is what we want:

http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/arch/x86/syscalls/syscall_64.tbl
bash-completion: rework startable/restartable units once more

I tried to use 'systemctl --all list-units' to filter unit files, but
this always filters out unit files which are not loaded. We want to complete
systemctl start with those units too, so this approach is not going to work.

New version is rather slow, but hopefully correct.
systemctl: let list-{units,unit-files } honour --type

The docs don't clarify what is expected, but I don't see any reason
why --type should be ignored.

Also restucture the compund conditions into separate clauses for
easier reading.
systemctl: obey --state in list-unit-files
bash-completion: use improved filtering to make things faster
zsh-completion: update start/restart completions

Now zsh should behave the same for those two subcommands as bash.