VFS: C99 sparse format for struct vfsops

[Terry Lambert]

Hiten Pandya wrote:
> My fingers have been itching to do this since the day phk@ planted this
> idea in my brain (re: cdevsw initialisations).  Basically, it changes
> the vfsops to use C99 sparse format, just like cdevsw.  It removes a lot
> of junk default initialisations, and duplication.

I really dislike the changes to vfs_init().  Specifically, it's
not the overhead, so much as it's the implied side effects.

Consider this going forward: someone adds a new VFSOP to the
list of allowable VFSOPs, and the vfs_init() doesn't have any
specific code for it.

This could happen with a new VFS implementation that gets loaded
as a module.  While the current code can't really handle this
well, the changes move us further away from ever being able to
handle something like this.  8-(.

-- Terry