build improvements: allow build mode selection (-g -G options) allow all exec build in one pass, remove remaining USE_MME macros in nr code

 - physical simulators
 - LTE eNB
 - LTE UE
 - 5G-NR gNB

Still NR-UE does not build and eNB segs fault at start of program

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

Mainly comestics and integer type management

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

Initial implementation.

nr_rlc/nr_rlc_oai_api.c will need some clean rewrite at some point.

More testing is also needed.

 - command line paramter --clock-source can only be set at UE (removed this option from gNB)
 - at gNB use clock_source from RU section in config file
 - in both cases if clock_source is present in usrp_args, it will override clock_source