WORKAROUND for 6765961 buffer modified while frozen

[darren.mof...@sun.com]

Author: Darren Moffat <Darren.Moffat at Sun.COM>
Repository: /hg/zfs-crypto/gate
Latest revision: 4403d4c7cf7a28a2f9f8de0a3331c6e05f508bd5
Total changesets: 1
Log message:
WORKAROUND for 6765961 buffer modified while frozen

Files:
        update: usr/src/uts/common/fs/zfs/arc.c
        update: usr/src/uts/common/fs/zfs/sys/zio.h
        update: usr/src/uts/common/fs/zfs/zio.c