shared: Clean up includes

Split out of #37344.

src/shared/edit-util.c

@@ -1,7 +1,8 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
-#include <errno.h>
 #include <stdio.h>
+#include <stdlib.h>
+#include <sys/stat.h>
 
 #include "alloc-util.h"
 #include "copy.h"