Fix: Teardown of thread_manage_clients on failure of listen/create_poll

Fix: Teardown of thread_manage_clients on failure of listen/create_poll

Currently, if the call to lttcomm_listen_unix_sock or
create_thread_poll_set fails, the error handling and thread teardown
code path is triggered via a jump to an error label. This error handling
path closes the sockets that were used and cleanup the poll set. If the
listen fails, the poll set will tentatively be cleaned even though it
has never been initialized.

This patch add 2 labels to differentiate the error handling paths needed
in case of failure of lttcomm_listen_unix_sock or
create_thread_poll_set.

Signed-off-by: Christian Babeux <christian.babeux@efficios.com>
Signed-off-by: David Goulet <dgoulet@efficios.com>