Adding mmap/munmap interfaces to file ops
Adding mmap/munmap interfaces to file ops

Context:ForestKVStore
Pre-req: http://review.couchbase.org/#/c/66763/

Change-Id: I3bd1b6396a983b105fe4f29144c69ba213c910b7
Reviewed-on: http://review.couchbase.org/66845
Reviewed-by: Chiyoung Seo <fcffc23db27b19ee4ebba46695ee6b50e09216a2@couchbase.com>
Tested-by: abhinav dangeti <d73ef2279de6577f7bf081737ee47554bbb7dc82@couchbase.com>

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