server: ensure that server pid file mem is always freed

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/server.c b/server.c
index beee2db..73866d7 100644
--- a/server.c
+++ b/server.c
@@ -1683,6 +1683,7 @@
 	if (check_existing_pidfile(pidfile)) {
 		log_err("fio: pidfile %s exists and server appears alive\n",
 								pidfile);
+		free(pidfile);
 		return -1;
 	}
 
@@ -1694,6 +1695,7 @@
 	} else if (pid) {
 		int ret = write_pid(pid, pidfile);
 
+		free(pidfile);
 		exit(ret);
 	}