MB-22010: Change the default eviction policy to statistical_counter
MB-22010: Change the default eviction policy to statistical_counter

This patch changes the default eviction policy from using the "2-bit_lru"
policy to using the "statistical_counter" policy.

Change-Id: I4c47a5def54259ad1f5025f2b9cc7458a0446cd3
Reviewed-on: http://review.couchbase.org/89098
Reviewed-by: Dave Rigby <a09264da4832c7ff1d3bf1608a19f4b870f93750@couchbase.com>
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>

daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine