plugins: pidfile: track PID file in svc, if svc has none declared

Services that create their own PID files usually don't declare one with
Finit.  This patch adds support to track those PID files anywayt at
runtime for the purpose of identifying match svc_t when a PID file is
removed, i.e. when a service exits.

 - On IN_CREATE the pidfile.so plugin saves the pid file name in svc_t
 - On ON_DELETE the pidfile.so plugin finds svc_t based on pid file

Quicker tracking and less dead code, win-win.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/svc.c

@@ -416,7 +416,17 @@ svc_t *svc_find_by_pidfile(char *fn)
 
 	pid = pid_file_read(fn);
 	if (pid <= 0) {
-		_d("pid_file_read(%s) => %d", fn, pid);
+		for (svc = svc_iterator(&iter, 1); svc; svc = svc_iterator(&iter, 0)) {
+			int v = 0;
+
+			if (svc->pidfile[0] == '!')
+				v = 1;
+			if (strcmp(&svc->pidfile[v], fn))
+				continue;
+
+			return svc;
+		}
+
 		return NULL;
 	}