It specifies that caller requests a fresh non-doomed vnode.  If doomed
vnode is found in the hash, it should behave similarly to FFSV_REPLACE.
Or, to put it differently, the flag is same as FFSV_REPLACE, but only
when the found hashed vnode is doomed.

Reviewed by:	chs, mkcusick
Tested by:	pho
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation