CBLT-42:  identify windows ARCH by "PROCESSOR_IDENTIFIER"

Change-Id: Id1ee9a370ed07ff77840a0b087b6d301439c59e3
Reviewed-on: http://review.couchbase.org/37108
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>