add rudimentary NRI support for MSC pooling

This patch served for a manual testing counterpart for osmo-bsc to implement
MSC pooling.

This enables a basic MSC pooling setup, but for a production setup, osmo-msc
would still lack various features related to unloading subscribers to another
MSC as explained in 3GPP TS 23.236.

Change-Id: Iafe0878a0a2c8669080d757b34a398ea75fced36
diff --git a/tests/msc_vlr/msc_vlr_test_authen_reuse.err b/tests/msc_vlr/msc_vlr_test_authen_reuse.err
index fc33b38..9b0dac2 100644
--- a/tests/msc_vlr/msc_vlr_test_authen_reuse.err
+++ b/tests/msc_vlr/msc_vlr_test_authen_reuse.err
@@ -1,6 +1,6 @@
 DLMGCP MGCP client: using endpoint domain '@mgw'
 full talloc report on 'msgb' (total      0 bytes in   1 blocks)
-talloc_total_blocks(tall_bsc_ctx) == 19
+talloc_total_blocks(tall_bsc_ctx) == 20
 
 ===== test_auth_use_twice_geran
 - Location Update request causes a GSUP Send Auth Info request to HLR
@@ -504,7 +504,7 @@
 ===== test_auth_use_twice_geran: SUCCESS
 
 full talloc report on 'msgb' (total      0 bytes in   1 blocks)
-talloc_total_blocks(tall_bsc_ctx) == 19
+talloc_total_blocks(tall_bsc_ctx) == 20
 
 ===== test_auth_use_twice_utran
 - Location Update request causes a GSUP Send Auth Info request to HLR
@@ -1036,7 +1036,7 @@
 ===== test_auth_use_twice_utran: SUCCESS
 
 full talloc report on 'msgb' (total      0 bytes in   1 blocks)
-talloc_total_blocks(tall_bsc_ctx) == 19
+talloc_total_blocks(tall_bsc_ctx) == 20
 
 ===== test_auth_use_infinitely_geran
 - Location Update request causes a GSUP Send Auth Info request to HLR
@@ -1644,7 +1644,7 @@
 ===== test_auth_use_infinitely_geran: SUCCESS
 
 full talloc report on 'msgb' (total      0 bytes in   1 blocks)
-talloc_total_blocks(tall_bsc_ctx) == 19
+talloc_total_blocks(tall_bsc_ctx) == 20
 
 ===== test_auth_use_infinitely_utran
 - Location Update request causes a GSUP Send Auth Info request to HLR
@@ -2288,7 +2288,7 @@
 ===== test_auth_use_infinitely_utran: SUCCESS
 
 full talloc report on 'msgb' (total      0 bytes in   1 blocks)
-talloc_total_blocks(tall_bsc_ctx) == 19
+talloc_total_blocks(tall_bsc_ctx) == 20
 
 ===== test_no_auth_reuse_geran
 - Location Update request causes a GSUP Send Auth Info request to HLR
@@ -2676,7 +2676,7 @@
 ===== test_no_auth_reuse_geran: SUCCESS
 
 full talloc report on 'msgb' (total      0 bytes in   1 blocks)
-talloc_total_blocks(tall_bsc_ctx) == 19
+talloc_total_blocks(tall_bsc_ctx) == 20
 
 ===== test_no_auth_reuse_utran
 - Location Update request causes a GSUP Send Auth Info request to HLR
@@ -3084,8 +3084,8 @@
 ===== test_no_auth_reuse_utran: SUCCESS
 
 full talloc report on 'msgb' (total      0 bytes in   1 blocks)
-talloc_total_blocks(tall_bsc_ctx) == 19
+talloc_total_blocks(tall_bsc_ctx) == 20
 
 full talloc report on 'msgb' (total      0 bytes in   1 blocks)
-talloc_total_blocks(tall_bsc_ctx) == 19
+talloc_total_blocks(tall_bsc_ctx) == 20