libmsc/gsm_09_11.c: introduce rate counters for NC_SS sessions
This change introduces some new rate counters for call-independent
SS/USSD connections. As OsmoMSC doesn't handle the messages itself,
and only responsible for dispatching messages between both
A and GSUP interfaces, the following is taken into account:
- MS-initiated and network-initiated requests to establish
a NC SS/USSD session (transaction) - "nc_ss:m{o|t}_requests";
- successfully established MS-initiated and network-initiated
SS/USSD sessions (transactions) - "nc_ss:m{o|t}_established".
Change-Id: I23c9475abc9951d82f3342fdc5aaa367836f7741
3 files changed