basic + fundamental: Clean up includes

Split out of #37344.

src/basic/time-util.h

@@ -1,24 +1,15 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 #pragma once
 
-#include <errno.h>
-#include <inttypes.h>
-#include <stdbool.h>
-#include <stddef.h>
-#include <stdint.h>
-#include <stdio.h>
 #include <time.h>
 
-typedef uint64_t usec_t;
-typedef uint64_t nsec_t;
+#include "forward.h"
 
 #define PRI_NSEC PRIu64
 #define PRI_USEC PRIu64
 #define NSEC_FMT "%" PRI_NSEC
 #define USEC_FMT "%" PRI_USEC
 
-#include "macro.h"
-
 typedef struct dual_timestamp {
         usec_t realtime;
         usec_t monotonic;