Windows: make lock reader history debug only

Windows: make lock reader history debug only

The lock reader history on osi_rwlock is proving to be too
expensive.  Only use it for DEBUG builds.  Leave the data
structures the same so that DEBUG builds can be mixed with
a RELEASE build of afsd_service.exe.

Change-Id: If0eeddb63c8f9919cdb5e119f31cde77974447b6
Reviewed-on: http://gerrit.openafs.org/6559
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>