Remove listmanager code

The code prevented scaling by imposing global spinlocks for the DCBs and
SESSIONs. Removing this list means that a thread-local list must be taken
into use to replace it.

server/core/gateway.cc

@@ -1935,11 +1935,6 @@ int main(int argc, char **argv)
         goto return_main;
     }
 
-    /* Temporary - should use configuration values and test return value (bool)
-     * TODO: Enable the list manager code */
-    dcb_pre_alloc(1);
-    session_pre_alloc(1);
-
     /** Initialize statistics */
     ts_stats_init();