Move vos COMMONPARMS to a larger offset

Currently, vos.c leaves a gap of 12 in the argument handling array
before its common operations (-verbose, -noauth, etc.); 'vos each'
will take more, so move that to 25.

While here, switch to named constants for these arguments, which
should make it easier to do this again, if ever necessary.

Change-Id: Idc4424e5fe4efd78389ea8421db000a361b461ec
Reviewed-on: http://gerrit.openafs.org/11332
Reviewed-by: Chas Williams - CONTRACTOR <chas@cmf.nrl.navy.mil>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>