In order to hook in via the "generic vnode" path for setting up
blockstores under FreeNAS, I've done a bit of shuffling in order to
make things more OS-independent and reusable.

* mkvnode.pl

Moved to clientside/tmcc/common.  OS-dependent bits (really only some
IPtables stuff) abstracted, and moved to tmcc/linux/libvnode.pm.

* libvnode.pm

Moved generic vnode stuff to a new module.  Moved miscellaneous
utility functions to a new module.  Left OS-specific stuff.  Not
really sure if what is left should be merged into libsetup/liblocsetup
or left here - deferring this decision for now.

* libgenvnode.pm

New module currently containing generic vnode stuff.  Currently, the
VNODE_* predicates are here.

* libutil.pm

New module containing miscellaneous utility functions (fatal,
mysystem, mysystem2, setState, etc.)

Files referencing libvnode.pm have been updated, as have the relevant
Makefiles.