include cleanups: remove unused headers and add feature test macros

src/dirent/fdopendir.c

@@ -3,8 +3,6 @@
 #include <sys/stat.h>
 #include <errno.h>
 #include <stdlib.h>
-#include <unistd.h>
-#include <limits.h>
 #include "__dirent.h"
 
 DIR *fdopendir(int fd)

src/dirent/opendir.c

@@ -1,11 +1,7 @@
 #define _GNU_SOURCE
 #include <dirent.h>
 #include <fcntl.h>
-#include <sys/stat.h>
-#include <errno.h>
 #include <stdlib.h>
-#include <unistd.h>
-#include <limits.h>
 #include "__dirent.h"
 #include "syscall.h"
 

src/dirent/readdir.c

@@ -1,11 +1,5 @@
 #include <dirent.h>
-#include <fcntl.h>
-#include <sys/stat.h>
-#include <errno.h>
-#include <stdlib.h>
-#include <limits.h>
 #include "__dirent.h"
-#include "syscall.h"
 #include "libc.h"
 
 int __getdents(int, struct dirent *, size_t);

src/dirent/readdir_r.c

@@ -1,6 +1,5 @@
 #include <dirent.h>
 #include <errno.h>
-#include <stdlib.h>
 #include <string.h>
 #include "__dirent.h"
 #include "libc.h"

src/dirent/scandir.c

@@ -1,10 +1,10 @@
 #include <dirent.h>
 #include <string.h>
 #include <stdlib.h>
-#include <inttypes.h>
+#include <stdint.h>
 #include <errno.h>
 #include <stddef.h>
-#include <libc.h>
+#include "libc.h"
 
 int scandir(const char *path, struct dirent ***res,
 	int (*sel)(const struct dirent *),