libosmogsm: add Routing Area Identifier test

Ensure that gsm48_parse_ra() and gsm48_construct_ra() behave properly.

Change-Id: I27117fe728407dd10886459e89ba4ff9d5e53e6b
diff --git a/tests/gsm0408/gsm0408_test.ok b/tests/gsm0408/gsm0408_test.ok
index 4a6d78b..f0abfd5 100644
--- a/tests/gsm0408/gsm0408_test.ok
+++ b/tests/gsm0408/gsm0408_test.ok
@@ -1,3 +1,11 @@
 Test `CSD 9600/V.110/transparent' passed
 Test `Speech, all codecs' passed
 Simple TMSI encoding test....passed
+Constructed RA: 6 - OK
+RA: MNC=121, MCC=77, LAC=666, RAC=5
+RA: MNC=121, MCC=77, LAC=666, RAC=5
+RA test...passed
+Constructed RA: 6 - OK
+RA: MNC=98, MCC=84, LAC=11, RAC=89
+RA: MNC=98, MCC=84, LAC=11, RAC=89
+RA test...passed