Added On-net UE_STATUS_INFO to notify the application based on the reception of SL specific RRC messages.

Testing with S1 interface works fine up to the reception of RRCConnectionSetupComplete from the eNB. Authentication problem occuring after that.

Modifications related to using single copies of nfapi config. messages for all the UEs at each subframe.

- fix compilation of dlsim/ulsim/oaisim by defining some needed
  global variables
- fix compilation of oaisim: compile coding and params_libconfig
- fix running of if4p5 with low CPU count (oaisim was not working
  on the machine 'haswell' because of this)

Fixed some more issues for running with multiple UEs. Added configuration option for the number of UEs.

More stable performance of nfapi-L2-emulator with 2 UEs, after dealing with some PNF-VNF synchronization issues.

This is only needed by the UE code, to setup IP settings.
The eNB does not need this. (To be reverted if this is
wrong.)

Fixed a bug. Now both UEs reaching RRC Connection Reconfiguration state about 90% of the executions. Less frequently appearing issues remain to be fixed.

It is possible to restart the lte-softmodem via the FlexRAN controller. For
this to work, the end_configmodule() method needs to be called when shutting
the lte-softmodem down so that the configuration can be read again during a
restart.

Extension to multiple UEs. Currently being tested with two UEs. Second UE doesn't always reach the RRC Connection Reconfiguration stage.

When the program exits it has to stop the streaming of the USRP.
The function exit_fun is supposed to do that. When quitting with
control+c (very common case) this function is not called. The
code is very unclear there, so let's add a stop_rf in the RU,
as there is already a start_rf.

If we don't call trx_end_func, then at the next run the USRP
device may be in an unstable state and behave improperly.

If the program crashes then the USRP device may be in an
unstable state. The only solution to this problem is to reset
the USRP device.

Maybe there is a way to clean the state of the device when we
open it, before we start using it. Sort of a cleanup before
use. That could be a better solution to "bad state after program
crash".

What has been tested:
- monolithic eNB only

The one in lte-enb.c disrupts the realtime. Using a B200mini with
20MHz bandwidth leads to the UE unable to connect for it seesms like
the UL and DL are not properly time synched because of this sleep
of one second that happens after the USRP streaming has started.
We see some random access attempts but the decoded preamble is
wrong.

This may be dependant on the setup. I had sporadic errors with
a B210, where sometimes the UE could connect and sometimes not.

Minor modifications. Some problem appears rarely that prevents the reception of RRCConnectionSetupComplete message at the eNB.

I tried to change rx and tx attenuation by the config file, but they are not changed. The bug is because att_rx and att_tx do not put in RC.rru when local_rf is "yes" in config file. We need to put att_rx and att_rx for both local_rf = "yes" and "no". Also RF config which send to RF device must be fill by this parameters.