Cleanup a memory leak in the daemons - thanks to Artem for spotting it
The TCP component will have set the hash table entry to NULL, but that doesn't remove the key. So the hash_table retrieval function will return success, but with a NULL pointer - protect against that scenario

Patch provided by Gilles - reviewed by rhc.

RM-approved

cmr=v1.8.2:reviewer=ompi-gk1.8