MFC r198703,r199156,r199157:

MFC r198703,r199156,r199157:

r198703:

- zfs_zaccess() can handle VAPPEND too, so map V_APPEND to VAPPEND and call
  zfs_access() instead of vaccess() in this case as well.
- If VADMIN is specified with another V* flag (unlikely) call both
  zfs_access() and vaccess() after spliting V* flags.

This fixes "dirtying snapshot!" panic.

PR:	kern/139806
Reported by:	Carl Chave <carl@chave.us>
In co-operation with:	jh

r199156:

Avoid passing invalid mountpoint to getnewvnode().

Reported by:	rwatson
Tested by:	rwatson

r199157:

Be careful which vattr fields are set during setattr replay.
Without this fix strange things can appear after unclean shutdown like
files with mode set to 07777.

Reported by:	des

git-svn-id: svn://svn.freebsd.org/base/stable/8@199266 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f