plugins: pidfile: reduce log noise

With the new practise of keeping record of process pid files, we no
longer need to log/update when reading back the same PID we already
have on file.

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

plugins/pidfile.c

@@ -91,9 +91,11 @@ static void pidfile_update_conds(char *dir, char *name, uint32_t mask)
 			pid_t pid;
 
 			pid = pid_file_read(pid_file(svc));
-			_d("Forking service %s changed PID from %d to %d",
-			   svc->cmd, svc->pid, pid);
-			svc->pid = pid;
+			if (pid != svc->pid) {
+				_d("Forking service %s changed PID from %d to %d",
+				   svc->cmd, svc->pid, pid);
+				svc->pid = pid;
+			}
 		}
 
 		cond_set(cond);