CONFIG_PID_FILE_PATH: new configuration option for pidfile paths

We set a default path for the directory where pidfiles are create
when FEATURE_PIDFILE is selected.  The default has no effect on
applets which must specify a pidfile path on the command line to
run, and it can be overridden by applets which optionally allow
the user to specify the pidfile path.

We also add pidfile write/remove support for klogd, ntpd and watchdog.
For syslogd, we add a missing remove_pidfile() for better cleanup
on daemon exit.

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

miscutils/watchdog.c

@@ -31,6 +31,7 @@ static void watchdog_shutdown(int sig UNUSED_PARAM)
 {
 	static const char V = 'V';
 
+	remove_pidfile(CONFIG_PID_FILE_PATH "/watchdog.pid");
 	write(3, &V, 1);  /* Magic, see watchdog-api.txt in kernel */
 	if (ENABLE_FEATURE_CLEAN_UP)
 		close(3);
@@ -95,6 +96,8 @@ int watchdog_main(int argc, char **argv)
 		stimer_duration, htimer_duration * 1000);
 #endif
 
+	write_pidfile(CONFIG_PID_FILE_PATH "/watchdog.pid");
+
 	while (1) {
 		/*
 		 * Make sure we clear the counter before sleeping,