MB-5305 use PRODUCT_VERSION instead of git_describe if it is set
MB-5305 use PRODUCT_VERSION instead of git_describe if it is set

Change-Id: I54df6117a16dc0923a3b3027fe2d64e7f72b4d48
Reviewed-on: http://review.couchbase.org/17136
Reviewed-by: Chiyoung Seo <8b279095f11c26cc21045fda5a3e51debb005aa9@gmail.com>
Tested-by: Chiyoung Seo <8b279095f11c26cc21045fda5a3e51debb005aa9@gmail.com>

owendCB/ep-engine,membase/ep-engine,couchbase/ep-engine,jimwwalker/ep-engine,membase/ep-engine,teligent-ru/ep-engine,teligent-ru/ep-engine,abhinavdangeti/ep-engine,couchbase/ep-engine,daverigby/kv_engine,sriganes/ep-engine,abhinavdangeti/ep-engine,membase/ep-engine,jimwwalker/ep-engine,daverigby/ep-engine,daverigby/kv_engine,daverigby/kv_engine,hisundar/ep-engine,daverigby/kv_engine,daverigby/ep-engine,owendCB/ep-engine,abhinavdangeti/ep-engine,abhinavdangeti/ep-engine,teligent-ru/ep-engine,daverigby/ep-engine,abhinavdangeti/ep-engine,sriganes/ep-engine,owendCB/ep-engine,jimwwalker/ep-engine,owendCB/ep-engine,teligent-ru/ep-engine,daverigby/ep-engine,couchbase/ep-engine,hisundar/ep-engine,sriganes/ep-engine,sriganes/ep-engine,hisundar/ep-engine,couchbase/ep-engine,membase/ep-engine,jimwwalker/ep-engine,hisundar/ep-engine