posix: sys/stat.h: declare missing types in sys/stat.h

After adopting the `<sys/stat.h>` header from picolibc, there is
a possibility that the following types are not defined.

```cpp
typedef int dev_t;
typedef int ino_t;
typedef unsigned short nlink_t;
typedef unsigned short uid_t;
typedef unsigned short gid_t;
typedef unsigned long blksize_t;
typedef unsigned long blkcnt_t;
```

Of the above missing types, the oonly ones that are used today
in Zephyr are `blksize_t` and `blkcnt_t`.

Signed-off-by: Chris Friedt <[email protected]>

Author: cfriedt

include/zephyr/posix/sys/stat.h

@@ -39,6 +39,41 @@ extern "C" {
 #include <sys/types.h>
 #include <sys/_timespec.h>
 
+#ifndef _DEV_T_DECLARED
+typedef int dev_t;
+#define _DEV_T_DECLARED
+#endif
+
+#ifndef _INO_T_DECLARED
+typedef int ino_t;
+#define _INO_T_DECLARED
+#endif
+
+#ifndef _NLINK_T_DECLARED
+typedef unsigned short nlink_t;
+#define _NLINK_T_DECLARED
+#endif
+
+#ifndef _UID_T_DECLARED
+typedef unsigned short uid_t;
+#define _UID_T_DECLARED
+#endif
+
+#ifndef _GID_T_DECLARED
+typedef unsigned short gid_t;
+#define _GID_T_DECLARED
+#endif
+
+#ifndef _BLKSIZE_T_DECLARED
+typedef unsigned long blksize_t;
+#define _BLKSIZE_T_DECLARED
+#endif
+
+#ifndef _BLKCNT_T_DECLARED
+typedef unsigned long blkcnt_t;
+#define _BLKCNT_T_DECLARED
+#endif
+
 /* dj's stat defines _STAT_H_ */
 #ifndef _STAT_H_