osmo-iuh decoding of MNC fixed

I've just pushed a fix of the BCD decoding for the MNC part of the RANAP PLMN-Id to master: osmo-iuh.git d8013d1f8caf1c38c9b4191f0bbb411f6a4ff9d6 (along with a few other commits)

BTW, my apologies for the unrelated and unnecessary cosmetic change in @@ -93,7 +98,8 @@ void test_asn1_helpers(void).

I've recently been pushing to osmo-iuh without posting for reviews, since the code is in flux and not in production use yet. Let me know if I should post patches instead.

~Neels