load-fragment: properly unescape \;

https://bugs.freedesktop.org/show_bug.cgi?id=87393
test-unit-file: add test for semicolon escaping

https://bugs.freedesktop.org/show_bug.cgi?id=87393
core: use raw_clone instead of fork in signal handler

fork() is not async-signal-safe and calling it from the signal handler
could result in a deadlock when at_fork() handlers are called. Using
the raw clone() syscall sidesteps that problem.

The tricky part is that raise() does not work, since getpid() does not
work. Add raw_getpid() to get the real pid, and use kill() instead of
raise().

https://bugs.freedesktop.org/show_bug.cgi?id=86604
networkd: Introduce Link Layer Discovery Protocol (LLDP)

This patch introduces LLDP support to networkd. it implements the
receiver side of the protocol.

The Link Layer Discovery Protocol (LLDP) is an industry-standard,
vendor-neutral method to allow networked devices to advertise
capabilities, identity, and other information onto a LAN. The Layer 2
protocol, detailed in IEEE 802.1AB-2005.LLDP allows network devices
that operate at the lower layers of a protocol stack (such as
Layer 2 bridges and switches) to learn some of the capabilities
and characteristics of LAN devices available to higher
layer protocols.
networkd: integrate LLDP

This patch integrates LLDP with networkd.

Example conf:
file : lldp.network

[Match]
Name=em1

[Network]
LLDP=yes