Add multi-host support

This refactoring includes:
- added multi-host mode support;
- added support for graceful shutdown of the service;
- added support to flush the log buffer as it fills;
- D-Bus service xyz.openbmc_project.HostLogger replaced with SIGUSR1
  signal handler;
- self diagnostic messages now registered via phosphor-logging;
- added unit tests;
- build system migrated from autotools to meson;
- source code aligned with OpenBMC conventions.

Change-Id: If6c1dfde278af685d8563450543a6587a282c7e4
Signed-off-by: Artem Senichev <a.senichev@yadro.com>
diff --git a/hostlogger@.service b/hostlogger@.service
new file mode 100644
index 0000000..73ebd00
--- /dev/null
+++ b/hostlogger@.service
@@ -0,0 +1,13 @@
+[Unit]
+Description=Host logger for %i
+BindsTo=obmc-console@%i.service
+After=obmc-console@%i.service
+
+[Service]
+ExecStart=/usr/bin/env hostlogger
+EnvironmentFile=/etc/hostlogger/%i.conf
+Restart=always
+SyslogIdentifier=hostlogger-%i
+
+[Install]
+WantedBy=multi-user.target