MB-10776: build NS_SERVER_VERSION based on PRODUCT_VERSION if available
MB-10776: build NS_SERVER_VERSION based on PRODUCT_VERSION if available

Change-Id: I9069a043d249fa97485cbaeb99c4ad351baf8ec5
Reviewed-on: http://review.couchbase.org/35421
Reviewed-by: Aliaksey Artamonau <3c875bcfb3adf2a65b2ae7686ca921e6c9433147@gmail.com>
Tested-by: Chris Hillery <cfae542fe86c678840b344434ba21c8613a98bd2@couchbase.com>

nimishzynga/ns_server,membase/ns_server,daverigby/ns_server,nimishzynga/ns_server,nimishzynga/ns_server,mschoch/ns_server,nimishzynga/ns_server,ceejatec/ns_server,t3rm1n4l/ns_server,t3rm1n4l/ns_server,daverigby/ns_server,ceejatec/ns_server,t3rm1n4l/ns_server,nimishzynga/ns_server,membase/ns_server,t3rm1n4l/ns_server,ceejatec/ns_server,mschoch/ns_server,ceejatec/ns_server,membase/ns_server,mschoch/ns_server,membase/ns_server,mschoch/ns_server,ceejatec/ns_server,daverigby/ns_server,daverigby/ns_server,mschoch/ns_server,t3rm1n4l/ns_server,daverigby/ns_server,mschoch/ns_server,ceejatec/ns_server,membase/ns_server,nimishzynga/ns_server,membase/ns_server