shared: Clean up includes

Split out of #37344.

src/shared/socket-netlink.c

@@ -1,21 +1,16 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
-#include <arpa/inet.h>
-#include <errno.h>
 #include <linux/net_namespace.h>
 #include <linux/unix_diag.h>
-#include <net/if.h>
 #include <string.h>
 #include <sys/stat.h>
 
 #include "sd-netlink.h"
 
 #include "alloc-util.h"
-#include "errno-util.h"
 #include "extract-word.h"
 #include "fd-util.h"
 #include "log.h"
-#include "memory-util.h"
 #include "namespace-util.h"
 #include "netlink-sock-diag.h"
 #include "netlink-util.h"