While sofia does garbage collection, in other locations we still call su_free…

While sofia does garbage collection, in other locations we still call su_free after calls to sip_header_as_string. So adding it here too since we've finished using the full_contact variable.

src/mod/endpoints/mod_sofia/sofia.c

@@ -8948,6 +8948,10 @@ void sofia_handle_sip_i_invite(switch_core_session_t *session, nua_t *nua, sofia
 		switch_assert(sql);
 
 		sofia_glue_execute_sql_now(profile, &sql, SWITCH_TRUE);
+
+		if ( full_contact ) {
+			su_free(nua_handle_home(tech_pvt->nh), full_contact);
+		}
 	}
 
 	if (is_nat) {