When decoding a constrained integer with a lower boundary, we need
to make sure the lower bound is added after decoding the raw offset
inside the range.
Before this change, RANAP_CauseMisc_unspecified_failure (115) would be
encoded as 2 (115 - 113 = 2), but would be decoded as 2, rather than
113+2 = 115.
Code for this was taken from
openairinterface5g/openair3/S1AP/MESSAGES/ASN1/asn1cpatch.p0 which
unfortunately doesn't carry much of a revision history :/
Harald Welte
20d668cbd3