fdtable: avoid pulling in posix header & types

Although fdtable sat a layer below posix, as part of
the base os, it was reaching up a layer for posix types,
creating another dependency cycle.

Generally, it would be best to use only ISO or native
zephyr types below POSIX, and these should likely be
removed after LTSv3.

Signed-off-by: Chris Friedt <cfriedt@tenstorrent.com>

include/zephyr/posix/sys/select.h

@@ -6,15 +6,13 @@
 #ifndef ZEPHYR_INCLUDE_POSIX_SYS_SELECT_H_
 #define ZEPHYR_INCLUDE_POSIX_SYS_SELECT_H_
 
-#include <zephyr/net/socket_types.h>
-#include <zephyr/net/socket_select.h>
+#include <zephyr/sys/fdtable.h>
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-#undef fd_set
-#define fd_set zsock_fd_set
+typedef struct zvfs_fd_set fd_set;
 
 #define FD_SETSIZE ZVFS_FD_SETSIZE
 

include/zephyr/sys/fdtable.h

@@ -6,14 +6,29 @@
 #ifndef ZEPHYR_INCLUDE_SYS_FDTABLE_H_
 #define ZEPHYR_INCLUDE_SYS_FDTABLE_H_
 
+#include <stdint.h>
 #include <stdarg.h>
-#include <sys/types.h>
 
-/* FIXME: For native_posix ssize_t, off_t. */
-#include <zephyr/fs/fs.h>
 #include <zephyr/kernel.h>
 #include <zephyr/sys/util.h>
 
+/* FIXME: avoid using POSIX types in layers below POSIX */
+
+#ifndef _SSIZE_T_DECLARED
+/* compiler complains when 'long' is used for both 32 and 64-bit */
+#ifdef CONFIG_64BIT
+typedef long ssize_t;
+#else
+typedef int ssize_t;
+#endif
+#define _SSIZE_T_DECLARED
+#endif
+
+#ifndef _OFF_T_DECLARED
+typedef int64_t off_t;
+#define _OFF_T_DECLARED
+#endif
+
 /* File mode bits */
 #define ZVFS_MODE_IFMT   0170000
 #define ZVFS_MODE_UNSPEC 0000000