Many variables were changed that should not have been changed.

Guess what happens when we return from the function...

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.

This reverts commit ce14050b, reversing
changes made to 0ada1e9e.

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.

Conflicts:
	openair1/PHY/INIT/lte_init.c
	openair1/PHY/LTE_TRANSPORT/dlsch_modulation.c
	openair1/PHY/LTE_TRANSPORT/power_control.c

The abstraction mode of oaisim does not work for the moment, it's better
to exit than to crash somewhere randomly.

	modified:   targets/COMMON/openairinterface5g_limits.h

                since two rx threads (even/odd) are used by OAI-UE

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.