tree-wide: Clean up includes

This commit cleans up the includes for all the small tools across
the tree.

A few cases of returning EXIT_SUCCESS are replaced with returning
0 to avoid including <stdlib.h>.

Split out of #37344.

src/initctl/initctl.c

@@ -1,11 +1,10 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
 #include <ctype.h>
-#include <errno.h>
+#include <signal.h>
 #include <stdio.h>
 #include <sys/epoll.h>
 #include <sys/stat.h>
-#include <sys/types.h>
 #include <unistd.h>
 
 #include "sd-bus.h"
@@ -18,15 +17,13 @@
 #include "constants.h"
 #include "daemon-util.h"
 #include "fd-util.h"
-#include "format-util.h"
 #include "initreq.h"
 #include "list.h"
 #include "log.h"
 #include "main-func.h"
-#include "memory-util.h"
-#include "process-util.h"
 #include "reboot-util.h"
 #include "special.h"
+#include "time-util.h"
 
 #define SERVER_FD_MAX 16
 #define TIMEOUT_MSEC ((int) (DEFAULT_EXIT_USEC/USEC_PER_MSEC))