sgsn_test: guard against struct gprs_ra_id changing

sgsn_test initializes various struct gprs_ra_id without naming the actual
members, which is vulnerable to struct member re-ordering. Name the members
explicitly.

An upcoming ABI change in libosmocore would cause test failures here without
this patch.

Change-Id: I517ed9edf77fac37d9de7a39df24c419a8a65d96
diff --git a/tests/sgsn/sgsn_test.c b/tests/sgsn/sgsn_test.c
index 4237349..2fbd6e4 100644
--- a/tests/sgsn/sgsn_test.c
+++ b/tests/sgsn/sgsn_test.c
@@ -1644,7 +1644,7 @@
  */
 static void test_gmm_ptmsi_allocation(void)
 {
-	struct gprs_ra_id raid = {332, 112, 16464, 96};
+	struct gprs_ra_id raid = { .mnc=332, .mcc=112, .lac=16464, .rac=96};
 	struct sgsn_mm_ctx *ctx = NULL;
 	struct sgsn_mm_ctx *ictx;
 	uint32_t foreign_tlli;
@@ -1847,8 +1847,8 @@
  */
 static void test_gmm_routing_areas(void)
 {
-	struct gprs_ra_id raid1 = {332, 112, 16464, 96};
-	struct gprs_ra_id raid2 = {332, 112, 16464, 97};
+	struct gprs_ra_id raid1 = { .mnc=332, .mcc=112, .lac=16464, .rac=96};
+	struct gprs_ra_id raid2 = { .mnc=332, .mcc=112, .lac=16464, .rac=97};
 	struct sgsn_mm_ctx *ctx = NULL;
 	struct sgsn_mm_ctx *ictx;
 	uint32_t ptmsi1;