Fix bugs in community flooding and TID forwarding.

Fix bugs in community flooding and TID forwarding.

Now uses "hostname:port" as the peer label instead of the gss credential
name. This allows the same label to be used to identify the local
trust router when avoiding community loops. Fixes several bugs that
prevented TID forwarding from working reliably, notably by properly
initializing the next pointer in a TR_AAA_SERVER structure to null.