mfi(4)/mfiutil(8): Add support for foreign configurations and drives.

mfi(4)/mfiutil(8): Add support for foreign configurations and drives.

For this, the following commands are added to mfiutil(8):

foreign scan - lists the number of foreign configs
foreign drives - lists the drives which are flagged as foreign
foreign display - displays the specified foreign configuration
foreign preview - previews the specified foreign configuration after import
foreign clear - clears the foreign configuration
foreign import - imports the foreign configuration

Foreign drive support has been added to 'show drives' too.

Tested-by:  ftigeot
Taken-from: http://www.freebsd.org/cgi/query-pr.cgi?pr=172091