Remove unused variable
Remove unused variable

couch-kvstore.cc:776:14: warning: variable 'newHeaderPos' set but not used
                         [-Wunused-but-set-variable]
     uint64_t              newHeaderPos = 0;

Change-Id: I8a7a6dd4997be011cadbe7db990b1a38aeffa4b3
Reviewed-on: http://review.couchbase.org/42231
Reviewed-by: Dave Rigby <a09264da4832c7ff1d3bf1608a19f4b870f93750@couchbase.com>
Tested-by: Trond Norbye <60edd2ef23891a753f231b0c6f161dc634079a93@gmail.com>
Reviewed-by: Sundararaman Sridharan <333a3f71d3ad6e01fc953c4fa06bc1f3cd014910@couchbase.com>

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