changed dirfd() to its POSIX signature, without const (see #4947).

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@40137 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/posix/dirent.h

@@ -41,7 +41,7 @@ int				closedir(DIR* dir);
 void			rewinddir(DIR* dir);
 void 			seekdir(DIR* dir, long int position);
 long int		telldir(DIR* dir);
-int				dirfd(const DIR* dir);
+int				dirfd(DIR* dir);
 
 int				alphasort(const struct dirent** entry1,
 					const struct dirent** entry2);

src/system/libroot/posix/dirent.c

@@ -279,7 +279,7 @@ telldir(DIR* dir)
 
 
 int
-dirfd(const DIR* dir)
+dirfd(DIR* dir)
 {
 	return dir->fd;
 }