include/ipc: Use the endpoint name as name for pubsub subscriptions

include/ipc: Use the endpoint name as name for pubsub subscriptions

When subscribing to a pubsub channel, a name constructed from the
hostname and pid is used for the subscription name. When multiple
processes subscribe to the same topic using the same endpoint, this
causes the endpoint to be subscribed multiple times, and multiple
messages to be received by the endpoint, when it should only receive
one message (this usage is intended for load-balancing over pubsub
channels).
This commit modifies the ipc module so that the name of the endpoint
is used for the subscription name, preventing an endpoint from being
subscribed multiple times to the same topic.