vos: convertROtoRW - prevent VLDB corruption

vos: convertROtoRW - prevent VLDB corruption

vos convertROtoRW incorrectly marks the first VLDB entry as the
new RW if the converted RO is not in the VLDB.  Correct this
by creating a new valid RW site in the VLDB entry.

Change-Id: I683ac10db90c2c41717c11c0d86eadc81a935e52
Reviewed-on: http://gerrit.openafs.org/8037
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>
(cherry picked from commit f258e7dddeb4331d2cf4649541c1a3adfa7a416a)
Reviewed-on: http://gerrit.openafs.org/8216
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>