Remove unused pieces in server_allocator_iface.h
Remove unused pieces in server_allocator_iface.h

The statistics is not used anymore

Change-Id: I0453d87d11ce0aeb6c1e4d9f1915871a0643aa8d
Reviewed-on: http://review.couchbase.org/120388
Reviewed-by: Jim Walker <1cd02e31b43620d7c664e038ca42a060d61727b9@couchbase.com>
Tested-by: Trond Norbye <60edd2ef23891a753f231b0c6f161dc634079a93@couchbase.com>

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