6386594 zdb message should be clearer when failing for lack of permissions

[nore...@opensolaris.org]

Author: mc142369
Repository: /hg/onnv/onnv-gate
Latest revision: 4390ea390a1ec1574ac3c7a6a3e972a2a4574da6
Total changesets: 1
Log message:
6386594 zdb message should be clearer when failing for lack of permissions

Files:
        update: usr/src/cmd/zdb/zdb.c
        update: usr/src/uts/common/fs/zfs/spa.c
        update: usr/src/uts/common/fs/zfs/vdev.c