Allow file path remap engine to create fifo nodes.
Note for fifos the copy_file is not called since
we will restore fifo data via pipe-data engine.

v2
 - no need for dev in mknod
 - don't reopen local copy on fifo files
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>