Refined logic so that if a shutdown is attempted and there is no
server.pid file, the 'fallback/2nd pass/assured shutdown' logic
to do a 'p4 admin stop' files only if a 'p4 info' command can
reach the server. Otherwise, the stop command is silently
Refined exit code handling and fixed log interaciton issues.
Fixed issue with systemd status not indicating successful startup.
The systemd unit files now specify the Type as simple rather than
forking, and defer to systemd to handle the forking. When systemd is
used, the -d/--daemonsafe flags are removed from service start commands
for p4p/p4broker/p4d, and for p4dtg the & is removed so the process is
not started in the background. For compatibility with non-systemd systems,
the -d/--daemonsafe flags are still applied when systemd is not in use.
With this change, systemd's concept of whether the service is running should
now be reliable. If you try to start without using systemd on a system for
which a systemd unit file exists, an error is displayed -- a big, hopefully
useful and informative error message.