msc_vlr_test_gsm_ciph: add test for GSM AKA in UMTS environment

Even on an R99 capable MS with a UMTS AKA capable USIM, the MS may still choose
to only perform GSM AKA, as long as the bearer is GERAN. In that case, we must
make sure to send the GSM AKA Kc for ciphering.

Add test_gsm_ciph_in_umts_env() to msc_vlr_test_gsm_ciph.c to answer an Auth
Request with a GSM AKA response (see the log stating "AUTH established GSM
security context" after we sent a UMTS AKA challenge).

In the test, show that we currently send the *wrong* Kc, i.e. the UMTS AKA
derived Kc for GERAN, instead of the correct Kc for GSM AKA (which was received
from the HLR in the auth tuples).

Subsequent patch I42ce51ae979f42d173a45ae69273071c426bf97c will fix this and
correct the test expectations.

Related: OS#2793
Change-Id: I85f12a20dcd701e671188e56811ec7b58d84da82
2 files changed