xserver lock order violation

xserver lock order violation

individual volume locks are pretty far down, well after afs_xserver.

afs_SetupVolume (with tv->lock)-> InstallUVolumeEntry-> afs_GetServer.

Install*Volume is careful to protect against recursing into the volume
lock via ResetVolumeInfo. Unfortunately, GetServer acquires xserver,
and then if it needs to call GetCapabilities, it drops and reacquires
xserver.

turns out the volume locks weren't protecting much. they also aren't
grabbed before xvolume is dropped. fine, so, restructure to do all the
work, then merge the result.

Change-Id: I648900849a5a7349adc686658872706bd7024c90
Reviewed-on: http://gerrit.openafs.org/5303
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>