logging: to the systemd journal

Configure via lvm.conf log/journal or command line --journal.

Possible values:
"command" records command information.
"output" records default command output.
"debug" records full command debugging.

Multiple values can be set in lvm.conf as an array.
One value can be set in --journal which is added to
values set in lvm.conf

lib/commands/toolcontext.h

@@ -42,6 +42,7 @@ struct config_info {
 	int udev_sync;
 	int udev_fallback;
 	int issue_discards;
+	uint32_t journal;
 	const char *msg_prefix;
 	const char *fmt_name;
 	const char *dmeventd_executable;