MB-19744: Move allocation of fdb_docs on to heap
MB-19744: Move allocation of fdb_docs on to heap

To avoid stack exhaustion, move allocation of the
list of fdb_docs on to the heap.

Change-Id: Ie131a53a13757480631dbb893db81ded472a2f3b
Reviewed-on: http://review.couchbase.org/64428
Well-Formed: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Chiyoung Seo <fcffc23db27b19ee4ebba46695ee6b50e09216a2@couchbase.com>
Tested-by: Chiyoung Seo <fcffc23db27b19ee4ebba46695ee6b50e09216a2@couchbase.com>

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