To be able to plugin different storage systems an abstraction
layer for the block storage is "required".
This is currently implemented in the existing block_if.{hc}
files.
The current callee access routings have their prefixes renamed
from blockif_ to locblk_.
And the caller parent functions now call blockbe_ functions.
(all this is more or less copied freely from net_backends.{hc})
Functional there should not be an change, other that the
calls to the storage API now go thru a an extra set of tabled
functions.