Prevent segfault in range encoding

* Explicitly check when ARFCN array split is impossible and return
  gracefully instead of using negative index.
* Separate range encoding into generic function and use it for all
  SI-related things.
* Propagate the error into that function and to its callers.
* Add separate test-case for the segfault previously triggered by this bug.

Change-Id: I3e049ab2d7c1c4d6c791b148f37e10636a8e43e0
Related: RT#7379
6 files changed
tree: 8c6655af403554274bd7a0486e888deda6329303
  1. contrib/
  2. debian/
  3. openbsc/
  4. .gitignore
  5. .gitreview
  6. .mailmap