• Don't make vgonel() globally visible, we want to change its prototype anyway and it's not used outside of vfs_subr.c.
• Change vgonel() to accept a parameter which determines whether or not we'll put the vnode on the free list when we're done.
• Use the new vgonel() parameter rather than VI_DOOMED to signal our intentions in vtryrecycle().
• In vgonel() return if VI_DOOMED is already set, this vnode has already been reclaimed.

Sponsored by: Isilon Systems, Inc.