For whatever reason, lte-softmodem.c was totally messed up...

We took the version from the branch develop and added
abstraction_flag, which is needed in openair2/LAYER2/MAC/main.c
(this is not clean, previous commit added a comment for this).
This has to be cleaned at some point.

The idea is as follows.

oaisim waits for all tasks to be done for a TTI.
To do so it waits for last_rx_timestamp == current_rx_timestamp,
for all UEs and eNBs.

When it's done, it increases current_rx_timestamp by samples_per_tti,
to inform UEs and eNBs that a new TTI is ready.

In the functions [UE|eNB]_trx_read, we wait for a new TTI to be ready,
that is we wait for current_rx_timestamp != last_rx_timestamp.

The UE has also to wait for processing threads to be done.
In the eNB it's not necessary because the processing is all
done in one thread, that is: read subframe, process this subframe,
emit subframe+4, and then back to read subframe.

The code is not clean. We should not use usleep but semaphores.

Also, do_[DL|UL]_sig should not read from rxdata and write to txdata,
but use internal buffers.

The functions [UE|eNB]_trx_read should call do_[DL|UL]_sig and then
copy from the internal buffers of the channel simulator into rxdata.

The functions [UE|eNB]_trx_write should write data passed into the
internal buffers of the channel simulator.

Not sure if this is the right thing to do, but it seems to be.

"start_eNB = 1;" is also necessary when the l2l1 task gets INITIALIZE_MESSAGE
otherwise the eNB does not start.

As it is today, I don't think oaisim will work with more than one eNB.

It's now done in lte-enb.c, even for oaisim.

It was probably the result of a bad merge.

At this point eNB_inst is not valid. Plus the T_ENB_MASTER_TICK
is now handled in lte-enb.c, even for oaisim.

oaisim is not functional with several UEs.
This fixes one issue. (It's still not functional for other reasons.)

We should use ENABLE_USE_MME, not USE_MME.
This code is useless anyway (I think, not sure, that's why I
leave it here), because the other threads wait for 'sync_var'
to become >=0.

	modified:   targets/COMMON/openairinterface5g_limits.h

Ip table clean use to run on oaisim shutdown. It is moved to run on oaisim starts.

In openairinterface5g many definitions in many layers of UE or eNB NB_MAX.
We created a file called openairinterface5g_limits.h
located at openairinterface5g_dir/targets/COMMON/ declaring the number max
of UE and eNB to be used in ALL layers depending on launching conditions
(LARGE_SCALE for example).

When using abstraction mode, layer2_init_UE() and openair_rrc_ue_init()
are called according to first_sync state and only without MME support.

We added the global variable abstraction_flag to allow abstraction mode
when MME is enabled.
Openair2 is also used in lte-softmodem, so it must have a global variable
abstraction_flag. So we moved it out from the main() scope.

TODO add option to conf2uedata and adapt script

changed the memory allocation of txdataF and beam_weigths

Beamforming is now only done when necessary. This patch is based on one from enhancement-10-harmony.

Some of them might not be correctly handled.
I put /* TODO: XXX */ where I didn't know if
the fix was correct.