gprs_ns2: add member name to bind

Every bind will have a unique name. Add a name argument
to all bind creating functions and require them to be unique.

This is an API break but there wasn't yet a release with NS2.

Change-Id: I8f1d66b7b3b12da12db8b5e6bd08c1beff085b3e
diff --git a/src/gb/libosmogb.map b/src/gb/libosmogb.map
index e3301be..7cc1cc8 100644
--- a/src/gb/libosmogb.map
+++ b/src/gb/libosmogb.map
@@ -109,6 +109,7 @@
 gprs_ns_msgb_alloc;
 
 gprs_ns2_aff_cause_prim_strs;
+gprs_ns2_bind_by_name;
 gprs_ns2_cause_strs;
 gprs_ns2_create_nse;
 gprs_ns2_dynamic_create_nse;