Address warnings seen while compiling on Windows
Address warnings seen while compiling on Windows

Of the like:
11:22:51 ..\ep-engine\src\ep_engine.cc(335) : warning C4101: 'error' : unreferenced local variable
11:22:51 ..\ep-engine\src\ep_engine.cc(341) : warning C4101: 'error' : unreferenced local variable

Change-Id: I50c7daf5d76f3ebdaba318d2fa65a8d377f7607b
Reviewed-on: http://review.couchbase.org/60064
Reviewed-by: Chiyoung Seo <fcffc23db27b19ee4ebba46695ee6b50e09216a2@couchbase.com>
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Trond Norbye <60edd2ef23891a753f231b0c6f161dc634079a93@gmail.com>
Reviewed-by: Dave Rigby <a09264da4832c7ff1d3bf1608a19f4b870f93750@couchbase.com>

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