"fs checkservers" during cache creation can crash client

"fs checkservers" during cache creation can crash client

Many pioctl calls pass as soon as the afs_resourceinit_flag is set,
which happens relatively early, alas before the cell name is set.
PCheckServers and others need the latter and dereference NULL.

Easiest: set the cell name as soon as it is known and the dynroot initialisation
piggy-backed to it can be done.

Change-Id: I9985f2c4a0afddfed04b85338108b3d6e97b64e6
Reviewed-on: http://gerrit.openafs.org/2072
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>