MFC r268764:
Check for the cross-device cross-link attempt in the VFS, instead of
VOP_LINK() implemenations.
MFC r268765:
Remove unused header.
MFC r269159:
Correct the locking statement.

MFC r269161:
Explicitely mention that inactivated or reclaimed vnode is locked
exclusively.
MFC r269160:
Remove man page for non-existent VOPs.

MFC r269240 (by pluknet):
Add VOP_GETVOBJECT.9 to obsolete files, un-xref.