basic: include only what we use

This is a cleaned up result of running iwyu but without forward
declarations on src/basic.

src/basic/dirent-util.h

@@ -22,8 +22,11 @@
 ***/
 
 #include <dirent.h>
+#include <errno.h>
+#include <stdbool.h>
 
 #include "path-util.h"
+#include "macro.h"
 
 int dirent_ensure_type(DIR *d, struct dirent *de);