import various generic IPA related functions from libosmo-abis

libosmo-abis is about forming A-bis interfaces/lines by means
of E1 or the IPA multiplex (or possibly other link layers).

The IPA multiplex is used in other contexts, such as the Control
interface, or the A interface.  In that context, it makes sense to
have generic IPA related functions in libosmocore.
4 files changed