Added the syscalls for sys_read_dir(), and sys_rewind_dir().

sys_read_dir() now has a parameter for the maximum number of dirents that
are handled by the upper layer - which is currently 1.
Added a comment in fd.h to ease the location of the sys|user prototypes
of the corresponding functions in fd.c.


git-svn-id: file:///srv/svn/repos/haiku/trunk/current@58 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/fd.h

@@ -73,6 +73,8 @@ void put_fd(struct file_descriptor *);
 void free_fd(struct file_descriptor *);
 static struct io_context *get_current_io_context(bool kernel);
 
+/* The prototypes of the (sys|user)_ functions are currently defined in vfs.h */
+
 
 /* Inlines */