T: isolate generated .h files when using make

When using the make system to generate T files, if you change
T_messages.txt you may have problems compiling the gnb with ninja.

If you want to see the problem:
First run: cd cmake_targets; ./build_oai --ninja --gNB
Then: cd common/utils/T
edit T_messages.txt, add a trace, for example:
---
ID = ENB_PHY_UL_TOCK
    DESC = eNodeB uplink tick - one tick per ms at start of uplink processing
    GROUP = ALL:PHY:GRAPHIC:ENB
    FORMAT = int,eNB_ID : int,frame : int,subframe
---
then run: make
then: cd cmake_targets/ran_build/build; ninja nr-softmodem
You should have an error looking like this:
---
[3/81] Checking validity of VCD files
FAILED: common/utils/T/CMakeFiles/check_vcd /tmp/develop/cmake_targets/ran_build/build/common/utils/T/CMakeFiles/check_vcd
cd /tmp/develop/cmake_targets/ran_build/build/common/utils/T && /tmp/develop/cmake_targets/ran_build/build/common/utils/T/_check_vcd /tmp/develop/common/utils/T/T_messages.txt /tmp/develop/common/utils/T/../LOG/vcd_signal_dumper.h
error: VCD_FIRST_VARIABLE is not correct in T_defs.h

You probably added a VCD trace (variable or function) but you did not
update T_messages.txt and/or T_defs.h in common/utils/T/
[...]
---

Let's first isolate the generated T .h files when using make because
we have two versions of T_IDs.h and T_messages.txt.h when mixing
make/cmake.

A next commit will regenerate T_IDs.h and T_messages.txt.h when
T_messages.txt chages for the cmake system, because this commit
does not solve the problem.

common/utils/T/tracee/tracee.c

@@ -6,7 +6,8 @@
 int main(void)
 {
   int frame = 0;
-  T_init(2021, 1, 0);
+  T_init(2021, 1);
+  T_stdout = 0;
   while (1) {
     getchar();
     T(T_ENB_PHY_PUCCH_1AB_IQ, T_INT(0), T_INT(0), T_INT(frame), T_INT(0), T_INT(0), T_INT(0));