build-sys: workaround scan-build bug to fix ./autogen.sh s

It seems to be a clang-analyzer problem since it don't behave like
clang-compiler regarding -std={c99,gnu99}
sd-ipv4ll: speed up bind() in the same way as for dhcp
build-sys: no use for compat libs in the static analysis
build-sys: remove no longer needed user/org.freedesktop.DBus.busname
sd-dhcp-client: use BPF on raw socket

Filter out everything except UDP packets destined for the DHCP client port,
this should avoid the vast majority of spurious wakeups.

Filter based on [0], with permission.

Possible improvemnts: also check for the DHCP magic cookie to drop invalid
packets. Check for our xid to filter out packets destined for other clients.

[0]: <https://github.com/ambrop72/badvpn/blob/master/dhcpclient/BDHCPClient.c#L57>
udev: do not export "static node" tags for non-existing devices
logind: don't print error if devices vanish during ACL-init

If a device is unplugged while we initialize it, we will get ENOENT for
ACL-init (and related stuff). We currently print errors then, which is
misleading. Print a debug-message early and continue.
networkd: drop routes when lease expires
networkd: smooth transition from ipv4ll to dhcp address

Currently when both ipv4ll and dhcp are enabled, ipv4ll
address (if one has been claimed) is removed when dhcp
address is aquired. This is not the best thing to do
since there might be clients unaware of the removal
trying to communicate.

This patch provides a smooth transition between ipv4ll
and dhcp. If ipv4ll address was claimed [1] before dhcp,
address is marked as deprecated. Deprecated address is still
a valid address and packets can be received on it but address
cannot be selected as a source address. If dhcp lease cannot
be extended, then ipv4ll address is marked as valid again.

[1] If there is no collision, claiming IPv4LL takes between 4 to
7 seconds.
sd-rtnl: fix broken test cases and add support for tunnel

This patch fixes the broken test-cases for sd-rtnl and add support for ipip
and sit tunnel.

[tomegun: minor fixups]
network: default to IPv4LL on host0

Now that we have a graceful handover from IPv4LL to DHCP, there is no longer any reason to leave this off by default.
bash completion: Add -r/--recursive to systemctl
bash_completion: busctl - add support for --user mode
backlight: do nothing if max_brightness is 0

On virtually any newer Asus mainboard, the eeepc-wmi driver is loaded.
It exposes a backlight device despite the lack of any physical backlight
devices. This fake backlight device has max_brightness set to 0. Since
the introduction of the clamp_brightness function, systemd-backlight
tries to write '1' to brightness and fails.

This patch changes systemd-backlight to exit gracefully when
max_brightness is 0 before performing any action. This affects
both the load and save actions.
journalctl: free arg_file on exit
journal: fix export of messages containing newlines

In "export" format, newlines are significant, and messages containing
newlines must be exported as "binary".
logind: remove one cast
systemctl: update NAME to PATTERN in help()

Previously the man page was modified, but not help().
tty-ask-password-agent: return negative errno

Return negative errno in wall_tty_block(). get_ctty_devnr() already
returns a negative errno in case of failure, no need to negate it again.

Reported-by: Simon <hwold@odai.homelinux.net>
Fix a few return codes in error paths