LoggedAtomic: Expand set of operations supported, serialize logging
LoggedAtomic: Expand set of operations supported, serialize logging

Add support for increment & decrement (fetch_{add,sub}), assignment
and conversion to T.

Also add a mutex to serialize access to stderr, to prevent corruption
in log messages.

Change-Id: I0a617f702a22d287fb87bd1001ee0300b6551b9e
Reviewed-on: http://review.couchbase.org/69009
Tested-by: buildbot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Daniel Owen <b3fc0e1a51f252986e60be7da121b74d3ac6845f@couchbase.com>
Reviewed-by: Jim Walker <1cd02e31b43620d7c664e038ca42a060d61727b9@couchbase.com>
Reviewed-by: Will Gardner <5d7e5a4e8e63c739e07f011adf51f2e51dd3ec09@rdner.io>

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