Destroy mutex while closing FileHandlePool in usecase_tests
Destroy mutex while closing FileHandlePool in usecase_tests

Change-Id: I2c2fbc144d3a1f0431912dfd3ba59e12699bd95b
Reviewed-on: http://review.couchbase.org/62743
Reviewed-by: Chiyoung Seo <fcffc23db27b19ee4ebba46695ee6b50e09216a2@couchbase.com>
Tested-by: Chiyoung Seo <fcffc23db27b19ee4ebba46695ee6b50e09216a2@couchbase.com>

wurikiji/forestdb,hisundar/forestdb,hisundar/forestdb,couchbase/forestdb,couchbase/forestdb,wurikiji/forestdb