* dtable.cc (dtable::build_fhandler): Add case for FH_MEM.
* fhandler.h: Add FH_MEM device type. Add class fhandler_dev_mem.
* fhandler_mem.cc: New file. Implementation of class fhandler_dev_mem.
* path.cc: Add /dev/mem to windows_device_names.
(get_device_number): Add FH_MEM type.