gsup: add OSMO_GSUP_RAT_TYPES_IE

Corresponds to the Supported RAT Types Indicator from 3GPP TS 29.002. See 8.1.2
MAP_UPDATE_LOCATION service.

This is useful to communicate the RAN / RAT type of the current subscriber
during Location Updating Request.

The use case we have in mind for VLR <-> HLR would require only a single RAT
type, but 29.002 specifies a list of supported RAT types. Hence implement this
as a list.

So far, have room for eight RAT types in the gsup_msg. That is an arbitrary
random choice without any rationale.

Change-Id: I93850710ab55a605bf61b95063a69682a2899bb1
diff --git a/tests/gsup/gsup_test.err b/tests/gsup/gsup_test.err
index 73b35fc..ea6fa15 100644
--- a/tests/gsup/gsup_test.err
+++ b/tests/gsup/gsup_test.err
@@ -101,26 +101,26 @@
 DLGSUP Stopping DLGSUP logging
   message 0: tested 2816 modifications, 510 parse failures
   message 1: tested 3584 modifications, 770 parse failures
-  message 2: tested 21248 modifications, 2575 parse failures
+  message 2: tested 21248 modifications, 2577 parse failures
   message 3: tested 2816 modifications, 510 parse failures
   message 4: tested 3584 modifications, 770 parse failures
-  message 5: tested 20736 modifications, 4022 parse failures
+  message 5: tested 20736 modifications, 4024 parse failures
   message 6: tested 3584 modifications, 771 parse failures
   message 7: tested 3584 modifications, 770 parse failures
   message 8: tested 2816 modifications, 510 parse failures
   message 9: tested 2816 modifications, 510 parse failures
   message 10: tested 3584 modifications, 770 parse failures
   message 11: tested 3328 modifications, 769 parse failures
-  message 12: tested 54016 modifications, 4626 parse failures
-  message 13: tested 11520 modifications, 1026 parse failures
+  message 12: tested 54016 modifications, 4628 parse failures
+  message 13: tested 11520 modifications, 1028 parse failures
   message 14: tested 5120 modifications, 1030 parse failures
-  message 15: tested 10752 modifications, 1262 parse failures
+  message 15: tested 10752 modifications, 1263 parse failures
   message 16: tested 7680 modifications, 1271 parse failures
   message 17: tested 8448 modifications, 2053 parse failures
-  message 18: tested 11264 modifications, 2307 parse failures
+  message 18: tested 11264 modifications, 2308 parse failures
   message 19: tested 5120 modifications, 1031 parse failures
   message 20: tested 6656 modifications, 1546 parse failures
   message 21: tested 3584 modifications, 771 parse failures
-  message 22: tested 5632 modifications, 771 parse failures
+  message 22: tested 5632 modifications, 772 parse failures
   message 23: tested 3584 modifications, 770 parse failures
   message 24: tested 3584 modifications, 771 parse failures