Allocate new conn structures with calloc.
Allocate new conn structures with calloc.

Janusz Dziemidowicz reported conn->next was sometimes not initialized.
This would have been the case for any client connection, or any
listener connection that wasn't tcp.

eklitzke/memcached,victorkirkebo/memcached,victorkirkebo/memcached,eklitzke/memcached,victorkirkebo/memcached,eklitzke/memcached