Remove some incomplete struct initializers

C99 requires that objects with static linkage, which includes
global variables, be initialized to zero/NULL.

It is possible that old compilers required a hack of using one
explicit initializer and relying on the requirement from C99 that
the elements of the structure not listed in the initializer be
initialized as if it had static linkage.  These incomplete initializers
seem to have been introduced to support old OS X compilers which
are not believed to still be in use.

Using a complete explicit initializer is undesired here, as the
rxkad statistics structures have a great number of elements and
the uuid structure is somewhat complicated.

Change-Id: Iefe7842cbf874252267cb3a8aee5d90ec2cab169
Reviewed-on: http://gerrit.openafs.org/11374
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Chas Williams - CONTRACTOR <chas@cmf.nrl.navy.mil>
Reviewed-by: Garrett Wollman <wollman@csail.mit.edu>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>