[RRC] support SIB18 (partially)

nfapi/open-nFAPI/nfapi/src/nfapi_p7.c

nfapi/open-nFAPI/pnf/src/pnf_p7.c

nfapi/open-nFAPI/pnf/src/pnf_p7_interface.c

openair2/LAYER2/MAC/config_ue.c

openair2/LAYER2/MAC/eNB_scheduler.c

openair2/LAYER2/MAC/eNB_scheduler_ulsch.c

openair2/LAYER2/MAC/ue_procedures.c

openair2/LAYER2/RLC/rlc_mac.c

openair2/PHY_INTERFACE/IF_Module.c

openair2/PHY_INTERFACE/phy_stub_UE.c

openair2/RRC/LITE/rrc_eNB.c

targets/RT/USER/lte-softmodem-stub.c

targets/RT/USER/lte-softmodem.c

targets/RT/USER/lte-softmodem.h

targets/RT/USER/lte-ue.c

targets/TEST/PACKET_TRACER/pt.c