Use FILE streams instead of ofstream
Use FILE streams instead of ofstream

The exceptions being thrown when we're seeing errors doesn't
give me much clue about what went wrong:

... due to IO exception "basic_ios::clear" ...

What should a user do with that information?

Change-Id: Iba9ba23a8bcf86728cf87401d2c4e628440f8763
Reviewed-on: http://review.couchbase.org/55190
Reviewed-by: Chiyoung Seo <fcffc23db27b19ee4ebba46695ee6b50e09216a2@couchbase.com>
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>

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