T: add a 'multi' tracer

This tracer allows the connection of several tracers to one tracee.

To use the multi tracer:
- run the tracee as usual, eg. ./lte-softmodem -O xxxx.conf --T_stdout 0
- run the multi tracer: ./multi -d ../T_messages.txt
- connect other tracers to the multi tracer:
   - ./enb -d ../T_messages.txt -p 2022
   - ./textlog -d ../T_messages.txt -p 2022
   - etc.

By default the multi tracer connects to the tracee to the port 2021,
as for any other tracer.

Then it accepts connections from other tracers on the port 2022.

This can be changed with parameters on the command line.

The tracee and the other tracers can be stopped/started at any time.

common/utils/T/tracer/Makefile

@@ -7,7 +7,7 @@ LIBS=-lm
 XLIBS=-lX11 -lpng -lXft
 
 all: record replay extract_config textlog enb ue vcd macpdu2wireshark \
-     extract_input_subframe extract_output_subframe to_vcd extract
+     extract_input_subframe extract_output_subframe to_vcd extract multi
 
 record: utils.o record.o database.o config.o
 	$(CC) $(CFLAGS) -o record $^ $(LIBS)
@@ -57,6 +57,9 @@ macpdu2wireshark: macpdu2wireshark.o database.o utils.o handler.o event.o \
                   config.o
 	$(CC) $(CFLAGS) -o $@ $^ $(LIBS)
 
+multi: multi.o utils.o database.o config.o
+	$(CC) $(CFLAGS) -o multi $^ $(LIBS)
+
 .PHONY: all gui/gui.a view/view.a logger/logger.a filter/filter.a
 
 gui/gui.a:
@@ -77,7 +80,7 @@ filter/filter.a:
 clean:
 	rm -f *.o core tracer_remote textlog enb ue vcd record replay
 	rm -f extract_config macpdu2wireshark extract_input_subframe
-	rm -f extract_output_subframe to_vcd extract
+	rm -f extract_output_subframe to_vcd extract multi
 	cd gui && make clean
 	cd view && make clean
 	cd logger && make clean