stp: Add tests for setups with multiple "routing context 0" ASPs

These two test cases verify that
* libosmo-sigtran doesn't include a routing context IE even in ASP
  role when using a ASP with a single routing context 0 configured
* osmo-stp can route between a single SG-role ASP with routing context
  to two ASP-role ASPs which both have routing context 0 (i.e. no
  routing context IE in use)

The tests do not pass with current libosmo-sigtran until OS#6003 is
fixed, presumably by Change-Id I5ce89b393a3b950ab7fd1eace9038718c9efcc51

Change-Id: I81052ece7d1cc8b43da6155356ed1c4d9620acdc
Related: OS#6003
diff --git a/stp/osmo-stp.cfg b/stp/osmo-stp.cfg
index 50c80d3..427eb34 100644
--- a/stp/osmo-stp.cfg
+++ b/stp/osmo-stp.cfg
@@ -53,6 +53,16 @@
   remote-ip 127.0.0.1
   sctp-role client
   role asp
+ asp asp-client60-norctx0 11060 2907 m3ua
+  local-ip 127.0.0.1
+  remote-ip 127.0.0.1
+  sctp-role client
+  role asp
+ asp asp-client61-norctx0 11061 2907 m3ua
+  local-ip 127.0.0.1
+  remote-ip 127.0.0.1
+  sctp-role client
+  role asp
  as as-sender m3ua
   asp asp-sender
   routing-key 1023 23
@@ -63,6 +73,12 @@
  as as-client m3ua
   routing-key 1055 55
   asp asp-client0
+ as as-client60-norctx m3ua
+  routing-key 0 60
+  asp asp-client60-norctx0
+ as as-client61-norctx m3ua
+  routing-key 0 61
+  asp asp-client61-norctx0
 !
 ! IPA AS/ASP:
 !
@@ -116,6 +132,8 @@
   update route 23 16777215 linkset as-sender
   update route 42 16777215 linkset as-receiver
   update route 55 16777215 linkset as-client
+  update route 60 16777215 linkset as-client60-norctx
+  update route 61 16777215 linkset as-client61-norctx
   update route 31 16777215 linkset ipa-as-loadshare-receiver
   update route 33 16777215 linkset ipa-as-override-receiver
   update route 5  16777215 linkset ipa-as-dynamic-asp