Rather than having the encoder/decoder library print some log
messages in case of encoding/decoding errors, let's provide something
akin to 'errno', but with a string instead of a numeric error code.
The 'osmo_cbsp_errstr' global variable (if set) contains a
human-readable string describing the most recent encoding/decoding error.
It exists separately for each thread and hence can be used safely in
multi-threaded environments.
Change-Id: Id9a5a595a76ba278647aee9470ded213d8464103
This introduces definitions as well as a parser+encoder for the
Cell Broadcast Service Protocol (CBSP) as specified in 3GPP TS 48.049.
CBSP is used on the interface between CBC and BSC.
Related: OS#3537
Change-Id: I5b7ae08f67e415967b60ac4b824db9e22ca00935