Added presence B2BUA. It may be used for doing SIP subscriptions for RLS module.

Makefile

@@ -53,7 +53,7 @@ exclude_modules?= 			acc cpl ext extcmd radius_acc radius_auth vm \
 							jabber mysql \
 							cpl-c \
 							auth_radius group_radius uri_radius avp_radius \
-							acc_radius dialog pa rls xmlrpc osp tls \
+							acc_radius dialog pa rls presence_b2b xmlrpc osp tls \
 							unixsock
 # always exclude the CVS dir
 override exclude_modules+= CVS $(skip_modules)