* fhandler.h (fhandler_base::mkdir): New virtual method.

* fhandler.h (fhandler_base::mkdir): New virtual method.
(fhandler_base::rmdir): Ditto.
(fhandler_disk_file:mkdir): New method.
(fhandler_disk_file:rmdir): Ditto.
* dir.cc (mkdir): Implement with fhandlers.
(rmdir): Ditto.
* fhandler.cc (fhandler_base::mkdir): New virtual method.
(fhandler_base::rmdir): Ditto.
(fhandler_disk_file::mkdir): New method.
(fhandler_disk_file::rmdir): Ditto.

fhandler_random.cc: white space.